Facts and figures ahead of Wednesday's Champions League first knockout round, second leg matches.

PORTO V SCHALKE 04

Head-to-head record:

Played: 3

Wins: Schalke 2, Draws 1

UF: R1 8.09.76 Porto 2 Schalke 04 2; 29.09.76 Schalke 04 3 Porto 2

CL: KO 19.02.08 Schalke 04 1 Porto 0

Previous appearances in last eight:

Champions League - Porto 5, Schalke 0

European Cup - Porto 7, Schalke 1

All European competitions - Porto 13, Schalke 6

* Porto, who have lost only one of their last 19 Champions League home games, have gone out in the knockout round in two of the last three seasons.

* Porto need two more goals to reach the tally of 400 in European competition. It is their 273rd game and they would become only the 15th club to reach this mark.

* Schalke have never lost to a Portuguese team in five meetings and have kept clean sheets in the last three.

* Schalke, aiming to reach the quarter-finals of the Champions League for the first time, are unbeaten in their last four Champions League games.

REAL MADRID V ROMA

Head-to-head record:

Played: 7 Wins: Real 4, Roma 2, Draws 1

CL: GP 11.09.01 Roma 1 Real Madrid 2; 24.10.01 Real Madrid 1 Roma 1

CL: GP 17.09.02 Roma 0 Real Madrid 3; 30.10.02 Real Madrid 0 Roma 1

CL: GP 28.09.04 Real Madrid 4 Roma 2; 8.12.04 Roma 0 Real Madrid 3

CL: KO 19.02.08 Roma 2 Real Madrid 1

Previous appearances in last eight:

Champions League - Real 8, Roma 1

European Cup - Real 27, Roma 2

All European competitions - Real 36, Roma 14

* Real, who aim to reach a record 28th European Cup quarter-final, are one of three teams seeking a record ninth appearance in the last eight of the Champions League. The others are AC Milan and Manchester United.

* Real have won their last five home games against Italian clubs and 16 of the last 19 but will be aware that they have only beaten Roma once in three previous Champions League matches in Madrid.

* Roma are unbeaten in their last five Champions League games but have lost their last three games in Spain.

* Roma have not kept a clean sheet in any of their last six Champions League games and have conceded 11 goals in their last four away.

CHELSEA V OLYMPIACOS

Head-to-head record:

Played: 1

Draws: 1

CL: KO 19.02.08 Olympiacos 0 Chelsea 0

Previous appearances in last eight:

Champions League - Chelsea 4, Olympiacos 1

European Cup - Chelsea 4, Olympiacos 1

All European competitions - Chelsea 10, Olympiacos 2

* Chelsea have kept clean sheets in their last five Champions League games and have let in just seven goals in their last 14, never conceding more than one in a game.

* Chelsea, playing in the knockout round for the fifth season in a row, are unbeaten in all seven games in the competition this season.

* Olympiacos, who are unbeaten in their last four Champions League games, have lost by at least two goals on each of their seven previous visits to England. They have scored just one goal and conceded 24 in those games, letting in four on four occasions.

* Olympiacos, quarter-finalists once before in 1999, have won two of their last three Champions League away games.

Reuters