Tottenham have to contend with Lionel Messi as they aim to progress in the Champions League, while PSG's Neymar will be eyeing a record.
The end of the Champions League group stage is closing in, and on Tuesday the likes of Tottenham, Inter, Paris Saint-Germain and Liverpool will learn their fate.
Most eyes will be on groups B and C, with several European giants at risk of being eliminated before the knockout phase.
Liverpool host Napoli, with both sides - as well as PSG, who face Red Star Belgrade - still able to go through from Group C, while Spurs travel to already-qualified Barcelona.
Mauricio Pochettino's Tottenham need to match the result Inter manage at home to PSV, meaning either they or the Serie A side will drop down to the Europa League after the turn of the year.
Below, we examine the key data from Tuesday's matches...
Schalke v Lokomotiv Moscow
8 - Schalke have not lost any of their last eight European home games (W5 D3 L0) – they last went longer without a home defeat in a continental competition between June 2003 and November 2004 (11 games).
9 - Lokomotiv are winless in their last nine away Champions League matches (D2 L7), losing each of their last four.
Galatasaray v Porto
3 - Galatasaray will be looking to keep three successive clean sheets at home in the Champions League within a single season for the first time since October 2001.
100 - Porto goalkeeper Iker Casillas has won 99 Champions League games – victory here will see him become the second player to reach 100 victories in the competition, after his former Real Madrid team-mate Cristiano Ronaldo.
Barcelona v Tottenham
30 - Since the start of the 1976-77 season, Barcelona have lost just one of their 30 European home matches against English clubs; this coming against Liverpool in February 2007 (1-2).
22 - Barca's Lionel Messi has scored 22 goals against English clubs in the Champions League; 10 more than any other player (Ronaldo on 12).
Inter v PSV
2 - Inter have lost two of their last five Champions League home group stage games (W2 D1), as many as they had in their previous 21 in San Siro (W15 D4 L2).
3 - Luuk de Jong has scored each of PSV's last three Champions League goals. The only players to get four consecutive goals for the Dutch side in the competition were Danny Koevermans in 2008 and Ruud van Nistelrooy ten years earlier.
Club Brugge v Atletico Madrid
47 - Atletico have kept a clean sheet in 47 per cent of their Champions League games (38/81). That is the best ratio of any team to have played more than 10 matches in the competition.
11 - Diego Simeone's men have faced fewer shots on target than any other Champions League side this season (11). However, they have conceded six goals, meaning they have let in
the highest percentage of shots on target faced in the competition (55 per cent).
Red Star Belgrade v Paris Saint-Germain
4 - PSG are winless in four successive Champions League away games (W0 D1 L3), their worst such run on the road in the competition since October 2012 (10 games in a row).
3 - Neymar scored a hat-trick in the home game against Red Star earlier this season – the only player to have scored two trebles against a single opponent in the same Champions League season was Luiz Adriano for Shakhtar Donetsk BATE in 2014-15.
Liverpool v Napoli
18 - Liverpool are unbeaten in 18 successive European matches at Anfield (W13 D5 L0), last losing at home in Europe back in October 2014 against Real Madrid (0-3).
8 - Mohamed Salah has scored eight goals in eight Champions League matches as a Liverpool player at Anfield – only Steven Gerrard (14) has netted more at home for the Reds in the competition than the Egyptian.
Monaco v Borussia Dortmund
6 - Monaco have lost six successive European home matches, scoring only three goals and conceding 17 in this period. Before this run, they had never previously lost more than two continental home games in succession.
2 - Should Monaco fail to win, they will be the first team to fail to win a single group stage game in two consecutive seasons of the Champions League since Dinamo Zagreb in 2011-12 and 2012-13.