In many ways, football is a simple game: the team that scores the most goals wins. Yet in every single match, there are intriguing statistical sub-plots that help make the beautiful game the fascinating spectacle that it is. That's why, each week, takes a look at the numbers behind the results.

This latest review stars two of the game's great 30-somethings, Ryan Giggs and Ronaldo, while the spotlight is also thrown on Chelsea's Camp Nou clean sheet, Napoli's surprise return to form and Jurgen Klinsmann's brief Bayern Munich reign.

800 Manchester United appearances is the milestone that Ryan Giggs will reach tonight if, as expected, he features in the Red Devils' UEFA Champions League semi-final against Arsenal. The veteran Welshman, who on Sunday became the oldest winner of England's PFA Player of the Year award at 35 years and 182 days, will also join Paul Scholes in becoming the first players to appear in six Champions League semi-finals for the same club. United, who have never been eliminated from Europe by another English club, are unbeaten in their 23 Champions League matches and are on course to be the first team to retain the European Cup since AC Milan in 1990. In Arsenal, however, the holders face a team with a 100 per cent record in their six European semi-finals to date, with the Gunners able to reflect on last four triumphs in 1970, 1980, 1994, 1995, 2000 and 2006.

504 minutes without a goal and 14 matches without a win: these were the sequences that came to the unlikeliest of ends for Napoli on Sunday. Given their status as Serie A's worst-performing club of 2009, the Azzurri's return to winning ways was unexpected enough, but the identity of the visitors to the Sao Paolo made it all the more surprising. After all, in Inter Milan, they were facing Italy's runaway leaders; a team that had lost just once in their previous 15 fixtures, and that over three months ago. Ironically, Marcelo Zalayeta, the man who ended Napoli's misery and left Inter without a win in Naples in the last 12 years, is the same player who halted the Nerazzurri's 31-game unbeaten run in the corresponding fixture last season.

301 days in charge of Bayern Munich made Jurgen Klinsmann the second-shortest-serving coach in the club's history. Only the Dane Soren Lerby, who spent just 155 days in charge of the Bavarian giants between October 1991 and March 1992, spent a more fleeting period at the helf. Bayern, who lost seven of their 29 league games under the former Germany coach and are just three points off the top of the league, have opted to replace Klinsmann with Jupp Heynckes, who won two successive Bundesliga crowns in 1989 and 1990 during a previous stint.

8 goals in 10 matches is the impressive haul accrued by Ronaldo since his return to action with Corinthians. Pele was among those who watched O Fenomeno bolster his tally with a double in Sunday's 3-1 victory over Santos in the first leg of the Paulista State Championship final, and the former Peixe star was gracious in his praise of the striker's brilliantly-executed second. "This was a goal worthy of a World Cup," enthused O Rei. "It was like a painting." Corinthians are even planning on making a film about the return of a player who spent over a year on the sidelines after suffering the latest in a series of career-threatening knee injuries in February of last year.

1 year and five days after they last failed to score at the Camp Nou, Barcelona drew a blank again last night as Chelsea left Catalonia with a precious clean sheet. Worryingly for the Blaugranas, the last team to shut them out at home was Manchester United, and no-one in Catalonia will need any reminding of how that particular Champions League semi-final turned out. Barça have now failed to win any of their last five home games against English opposition, and Chelsea have proved especially troublesome. The Londoners are unbeaten in their last four European meetings with Barcelona, a record that only one other club - Manchester United - can match.