The transfer window - summer or winter - follows a familiar pattern: a slow start, with a gradual crescendo of activity, culminating in a frenzy of business in the last few hours. The latest January window is no different, and after a gentle initial period, the number of deals being sealed as we reach the midway point is starting to multiply. looks back on all of the key transfers concluded over the last two weeks.

The Premier League offers the best illustration of the build-up of activity over the duration of the window. Up until now, things have been relatively calm, but English clubs are now starting to step up their activities, none more so than Chelsea who have pulled off the transfer window's biggest coup to date. Concerned by the loss of two of their forwards, Didier Drogba and Salomon Kalou, who have departed on CAF Africa Cup of Nations duty, the Blues moved to secure a deal for Nicolas Anelka.

At 29, the Frenchman is returning to London eight-and-a-half years after leaving Arsenal with the hope that this will be the last move in a career that has taken him across virtually the whole of Europe. "Chelsea were the club who wanted me, and I hope that this will be the last team I play for," said Anelka after making his debut against Tottenham Hotspur. "I've shown that I can score goals at the highest level and I can do the same for Chelsea. I won't let them down." The Blues have also reinforced their defence, recruiting the Serbian international centreback Branislav Ivanovic, who has joined from Russian club Lokomotiv Moscow.

Liverpool have also turned to the Russia in order to bolster their rearguard by signing the Slovak international Martin Skrtel, who recently helped Zenit St Petersburg win the Russian Premier League title. At 23, he has played 15 times for his country and is expected to take the place of Danish centre-back Daniel Agger, who has been out with a long-term injury. Liverpool's local rivals Everton, meanwhile, have signed Portuguese midfielder Manuel Fernandes, who spent the final six months of last season on loan at Goodison Park. Fernandes played nine times for the Toffees in the Premier League last season, scoring twice.

Basement boys' spending spree
Hopelessly rooted to the bottom of the table, Derby County are going all out to maintain their place in the top flight. A frenzy of activity in the transfer market has seen the Rams sign French winger Laurent Robert, Argentinian forward Emanuel Villa, Welsh midfielder Robbie Savage and the former England international right-back Danny Mills. The recent arrival of Egyptian international midfielder Hossam Ghaly from Spurs brings their tally of new recruits so far to five.

Wigan Athletic, who face a similar task to Derby County, have recruited Honduran pair Maynor Figueroa and Wilson Palacios from Deportivo Olimpia, though Palacios already has experience of the Premier League, having spent last season on loan at Birmingham City. The Blues have themselves been busy in the transfer market, though their signings have a distinctly Tartan flavour, with former Scotland manager Alex McLeish bringing his compatriot James McFadden to St Andrews from Everton and plundering Edinburgh club Hibernian for left-back David Murphy. Bolton Wanderers, meanwhile, have begun life without Nicolas Anelka by recruiting Iceland defender Gretar Steinsson from AZ Alkmaar and Portsmouth utility man Matt Taylor.

Pompey, in turn, have recruited a full-back to reinforce the other side of their defence. Just five months after joining Arsenal from Chelsea, French international Lassana Diarra has left London to sign for Harry Redknapp's side.

South American exodus to the Bundesliga
The trend in Germany these days is to recruit players from South America. Doubtless convinced by the impressive performances of their Brazilian pair Marcelo Bordon and Rafinha, and their Uruguayan recruit Carlos Grossmuller, Schalke 04 have returned to Latin America to sign Mexican forward Vicente Sanchez, who scored 85 goals for Toluca in the Mexican Championship after joining them in 2001. Further bolstering the South American contingent at Schalke is Brazilian attacking midfielder Ze Roberto, who arrives from Botofogo and who will soon find himself crossing paths with his Bayern Munich namesake.

Hertha Berlin and Eintracht Frankfurt have also been busy snapping up Brazilians. The Berliners have signed striker Raffael, who scored 39 goals in 77 appearances for FC Zurich, while Eintracht have recruited Caio, a young attacking midfielder who joins from Palmeiras. FC Nuremberg have been shopping for bargains close to home, and have managed to secure the signing of Monaco's experienced Czech hitman Jan Koller. Koller makes his return to Bundesliga, 18 months after leaving Borussia Dortmund for the Principality. He is now 34, but has lost none of his sharpness in front of goal, and remains the most prolific marksman in the history of the Czech national team. He has been quick to find his feet for his new side, impressing during two mid-season friendlies.

The French league may have lost one of its top forwards to Germany, but it has gained a highly-rated Argentinian forward in the form of Cesar Delgado. After scoring 95 goals in just 132 games for Mexican club Cruz Azul, and with a further two goals from 20 international appearances, El Chelito has joined Lyon as he bids to make his mark on European football. "I'm coming to a prestigious club with a great history. I hope that they are going to continue their climb to the top," said the Argentinian on arriving in France. "I'm very quick, and I can play on the right or the left. I know how to deliver good crosses and provide ammunition for the centre-forward."

Canny recruitment
The six-times French champions have made several signings, including the young Spanish midfielder Marc Crosas, who has joined on loan from Barcelona. Heading out of the door, meanwhile, is defensive midfielder Fabio Santos, who has returned to his native Brazil to join Sao Paulo on loan. Also leaving the club is Algerian left-back Nadir Belhadj, who has failed to establish himself in the first team since joining a year ago. He will be looking for a new start with RC Lens, and could make his debut this Sunday - against Lyon.

Nice, who are past masters when it comes to pulling off transfer coups, and who currently lie a surprising fifth in the table, have brought back defender Gerald Cid, who left Bordeaux to join Bolton Wanderers at the start of the season, but who failed to break into the Trotters' team. Another club well versed in the art of unearthing transfer market bargains are Le Mans, who are hoping to continue their fine start to the season and have engaged the services of Tunisian right-back Saber Ben Frej from L'Etoile and the Brazilian central defender Antonio Geder, who arrives from Spartak Moscow.

In Italy, the main activity has focused around the club who are seemingly in least need of reinforcements. Unbeaten so far this season, and with a solid lead at the top of the Serie A table, Inter Milan have nonetheless decided to add to their squad with the recruitment of Portugal's defensive midfielder Maniche. Unable to secure regular place at Atletico Madrid, the former Porto player and UEFA EURO 2004 winner will undoubtedly have a useful role to play in Roberto Mancini's plans, as he helps to strengthen a midfield that has been weakened by injuries to Luis Figo, Patrick Vieira, Olivier Dacourt and Dejan Stankovic.

Return of the prodigals
The other Italian club to pull off a major coup this month are Parma, who have moved to repatriate Cristiano Lucarelli. Scorer of 20 goals last season for his hometown club Livorno, Lucarelli left Serie A in the summer to sign for Shakhtar Donetsk. However, the Ukrainian club's early exit from the Champions League, and his failure to adapt to life in Ukraine, have prompted a swift return home. If he manages to repeat his performances of previous seasons, there is no doubt that Lucarelli will be able to stake a major claim for a placed in the Azzurri squad for EURO 2008.

Several other expats have returned home this winter. Striker Cristiano Rigano and defender Bruno Cirillo, have left Spain's bottom club Levante to head back to Italy, joining Siena and Reggina respectively. Goalkeeper Marco Storari meanwhile has moved to another relegation-threatened club, Cagliari.

In Spain, the transfer market has been very quiet so far. However, elsewhere in Europe, things have been getting busy. Greek football has welcomed the arrival of two experienced forwards, Brazilian Marcio Amoroso, who has enjoyed previous stints in Japan, Germany, Italy and Spain, and who has signed an 18 month contract with Aris Saloniki, and the Portuguese international striker Helder Postiga, who has moved to Panathinaikos on loan from Porto. In Scotland, meanwhile, Celtic have paid £1.9 million to Sevilla for German international full-back Andreas Hinkel.

On the other side of the Atlantic, meanwhile, the main clubs have been equally busy bolstering their squads with experienced signings. Several seasoned stars have left Europe this January to return to Latin America. Former Brazil international midfielder Vampeta, a veteran of both Inter Milan and PSG, has signed for Sao Paulo outfit CA Juventus. Meanwhile, Diego Placente, a UEFA Champions League finalist with Bayer Leverkeusen in 2002, has returned home to Argentina in time to turn out for San Lorenzo in the Copa Libertadores, six months after leaving Spanish club Celta Vigo. He will soon come face to face with his compatriot Lucas Castroman, who will line up for fellow Argentinian club Boca Juniors, who he has joined on loan from Mexican side America.

The transfer window remains wide open until 31 January. Before then, clubs around the world will continue their endeavours to bolster their squads. Be sure to stay tuned to in order to keep up with all the latest deals from every corner of the planet.