The round of 16 of the UEFA Champions League begins this week with the first four first-leg matches. The remaining four will be played next week, with the return legs taking place in the first two weeks of March.

Nine nations are represented among the 16 surviving sides. Spain is the only country with four teams still in the running, followed by Germany with three, and Italy and England with two apiece, the second year in a row that the Premier League has had such low representation.

Three of the eight ties pit together previous winners of the competition, as Celtic take on Juventus, Real Madrid meet Manchester United and AC Milan do battle with Barcelona. Meanwhile, Spain’s Malaga are the first newcomers at this stage of the competition since Lokomotiv Moscow in 2003/2004.

For the 23rd time in a row this year’s competition will not be won by the defending champions, with last season’s winners Chelsea having already fallen by the wayside in the group phase.

This week’s fixtures
Tuesday 12 February
Valencia-Paris Saint-Germain 

Wednesday 13 February
Shakhtar Donetsk-Borussia Dortmund
Real Madrid-Manchester United

Match of the day
Real Madrid-Manchester United, Santiago Bernabeu, Madrid, 20:45 CET
These two giants have been crowned European champions 12 times between them. Trailing all of 16 points behind Barcelona in the league, Real Madrid are aiming to salvage their season by winning the famous trophy for a tenth time. In contrast, Manchester United have built up a commanding 12-point lead in the English Premier League and are looking to extend their impressive record of having reached three Champions League finals in the last five seasons. The two sides have played each other eight times in the competition, the Spaniards having a slight edge with three wins to United’s two, the remaining three meetings ending all-square.

In response to his side’s spluttering domestic form, Jose Mourinho reshuffled his pack for last Saturday’s league match with Sevilla, sending out an ultra-offensive line-up featuring Luka Modric, Kaka, Gonzalo Higuain, Karim Benzema and Cristiano Ronaldo. The resulting 4-1 romp, complete with a stunning Ronaldo hat-trick, proved reassuring for the Madrid giants, who are nevertheless unlikely to adopt such a bold approach against a solid United side that poses a genuine threat on the counter. Unbeaten at home in the competition since losing 2-0 to Barcelona in the semi-finals in 2011, Madrid will be hoping that record remains intact come the final whistle on Wednesday.

The other matches 
Celtic coach Neil Lennon should have no trouble motivating his side, having formed part of the side that famously beat Juventus 4-3 in a group match at Celtic Park on 31 October 2001. Eighteen points clear at the top of the Scottish Premier League, the Hoops are unbeaten in their last eight home meetings with Italian sides, a run that stretches back to 12 March 1969. Runners-up in Group G, having finished ahead of Benfica and Spartak Moscow, Celtic claimed a notable scalp in beating Barcelona in Glasgow, and will need to produce the form they found that night if they are to find a way past the in-form Gianluigi Buffon, who was on the bench for that seven-goal thriller over 11 years ago. On top in Serie A since the start of the season, Juve are unbeaten in their last 16 European outings.

Valencia-Paris Saint-Germain
Following a problematic start to the season, Valencia have rediscovered their form under coach Ernesto Valverde, who favours a 4-2-3-1 formation spearheaded by Spain striker Roberto Soldado. Habitually tough opposition at their Mestalla fortress, where they are unbeaten in their last nine Champions League games, Los Chés have a perfect record at home to French teams, having won eight out of eight meetings with them in their backyard. In topping their group Ligue 1 leaders PSG lost just once, away to Porto, but will be without three of their star acts in Spain, with Thiago Motta and Thiago Silva both injured and new arrival David Beckham still not fully match-fit.

Shakhtar Donetsk-Borussia Dortmund
Well in command in the domestic championship race, Shakhtar Donetsk, who qualified at holders Chelsea’s expense, are aiming to reach the last eight for only the second time in their history. Their wily Romanian coach Mircea Lucescu will be banking on his eight-strong Brazilian contingent to see off the Germans, though he also has a potent weapon in Armenian attacking midfielder Henrikh Mkhitaryan, the Ukrainian league’s top scorer with 18 goals. Dortmund pulled off a major feat in topping a very tough section that also featured Real Madrid, Ajax and Manchester City, and have grounds for confidence, having not lost any of their previous six encounters with Ukrainian sides. Jurgen Klopp’s men have fallen well off the pace in the Bundesliga, however, and now trail runaway leaders Bayern Munich by 15 points after Saturday’s 4-1 loss at home to Hamburg.
Player to watch
Now 33 and 20 years a professional footballer next season, Andrea Pirlo remains at the peak of his powers, a point he proved in a virtuoso display in Saturday’s 2-0 victory over Fiorentina. From his 118 touches against La Viola, the peerless playmaker completed 74 passes out of 75. Since arriving in Turin in May 2011 he has become an indispensable part of a Juve line-up that is once again harbouring dreams of European glory.

The stat  
15 - The final quarter of an hour of this season’s Champions League matches has produced 50 goals, more than any other 15-minute period. The final third of the first half has yielded 48, the next-highest amount, with the opening 15 minutes throwing up only 31 goals.
What they said
“After the match against Granada (when a Ronaldo own goal consigned Madrid to a 1-0 defeat) and the image we projected, it was important for us to clear any doubts from our minds. And Ronaldo came up with the best possible response,” Real Madrid assistant coach Aitor Karanka on Saturday’s 4-1 drubbing of Sevilla.

Have your say
Who will win the goalscoring duel between Real Madrid triumvirate Cristiano Ronaldo, Gonzalo Higuain and Karim Benzema and Manchester United twosome Wayne Rooney and Robin van Persie?