UEFA.com looks at the key statistics from this week's games, when Lionel Messi and Luiz Adriano managed notable scoring feats and Andrea Pirlo marked a century in style.
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• Lionel Messi's double for FC Barcelona at AFC Ajax enabled him to move level with Raúl González as the UEFA Champions League's all-time top scorer on 71 goals. Cristiano Ronaldo missed the chance to reach that number by failing to score the previous evening as Real Madrid CF beat Liverpool FC 1-0.
• Messi had one of his own records matched the same evening as FC Shakhtar Donetsk striker Luiz Adriano became only the third player to score two hat-tricks in the same UEFA Champions League campaign; Mario Gomez was the other, both he and Messi managing that feat in 2011/12. Luiz Adriano became the first player to score a hat-trick in successive matches in the competition.
• Luiz Adriano also became only the fourth player to register more than two UEFA Champions League hat-tricks. Messi leads the way with four, with the Shakhtar striker joining Filippo Inzaghi and Gomez on three. Cristiano Ronaldo has two.
• Luiz Adriano now has nine goals for the season, matching Ronaldo's group stage record set in 2013/14.
• The goal with which Luiz Adriano completed his hat-trick was his 20th in the UEFA Champions League. He is the 37th player to reach that tally and the fifth Brazilian after Kaká (30 goals), Rivaldo (27), Mário Jardel (25) and Giovane Elber (25).
• Seydou Doumbia's double against Manchester City FC lifted the PFC CSKA Moskva striker's all-time tally in the competition to ten. He is the 120th player to reach double figures.
• Andrea Pirlo became the 23rd player – and only the second Italian, after Paolo Maldini – to reach a century of UEFA Champions League appearances when he started Juventus' 3-2 win at home to Olympiacos FC. He celebrated the achievement by scoring the Bianconeri's opening goal with a trademark free-kick.
• FC Porto's 2-0 win at Athletic Club came in the Portuguese side's 150th UEFA Champions League match, with only six other clubs having played more. Matchday four also marked the 100th game in the competition for Ajax. Unlike Porto, however, the Amsterdam outfit were unable to celebrate their accomplishment with a victory, going down 2-0 at home to Barcelona.
• Real Madrid's Iker Casillas and Barcelona's Xavi Hernández kept pace with each other by making their record-extending 144th UEFA Champions League appearances on matchday four.
• Madrid's defeat of Liverpool in the Santiago Bernabéu was their tenth successive home win in the competition, eclipsing not only their own UEFA Champions League record of nine – set between March 1996 and December 1998 – but also those of AC Milan, FC Barcelona and FC Bayern München. Madrid are now level with Juventus and closing in on the competition record of 12 straight home wins set by Manchester United FC between September 2006 and April 2008.
• The win against Liverpool was also Madrid's 20th successive home game in the competition without defeat. The record is 29 matches, set by FC Bayern München between March 1998 and April 2002.
• Breel Embolo became the sixth youngest scorer in the UEFA Champions League with the first goal in FC Basel 1893's 4-0 win at home to PFC Ludogorets Razgrad, aged 17 years and 263 days. He is the eighth player under the age of 18 to score in the competition. The record is still held by Olympiacos' Peter Ofori-Quaye, who was 17 years and 195 days old when he found the net against Rosenborg BK in October 1997.
• Three points apiece on matchday four for Real Madrid, Barcelona and Club Atlético de Madrid mean that Spain now boasts a 50% win percentage in the competition – the best of all participating countries – with 344 victories in 688 matches.
• For only the third time, all four English clubs failed to win on a UEFA Champions League group stage matchday. The two previous occasions were matchday six in 2005/06 and 2008/09 matchday four.
Mike Hammond is the editor of the European Football Yearbook, the 2014/15 edition of which is out now.