The Champions League's round of 16 continues on Tuesday, when Turkish champions Besiktas, one of four teams unbeaten in this season's tournament, travel to face Bundesliga heavyweights Bayern Munich.

Another side yet to taste defeat in Europe is Barcelona, who renew acquaintances with regular continental foes Chelsea.

Lionel Messi will be seeking to finally score against the Blues, while Luis Suarez is also desperate to end a Champions League dry spell.

Here, we look at the best of the Opta numbers ahead of these two crunch clashes…

Bayern Munich v Besiktas 

6 - Bayern have reached the Champions League semi-finals in six of the last eight seasons. Meanwhile, this is the first time Besiktas have reached the knockout stages of the competition.

19 - At the Allianz Arena, Bayern have won 19 of their last 20 Champions League games, the only exception coming against Real Madrid in last season's quarter final (1-2). 

3 - Besiktas are the only side to have won all three of their away games in the Champions League this season. They were also one of four teams to remain unbeaten in this season's group stages, alongside Barcelona, Liverpool and Tottenham.

17 - Robert Lewandowski has scored 17 goals in his last 16 Champions League appearances at the Allianz Arena. Of the players to have featured in at least 20 knockout games, he has the second-best goals per game (0.68) behind Cristiano Ronaldo (0.79).

71 per cent - Jupp Heynckes, winner of two Champions League titles as manager (Real Madrid 1998, Bayern Munich 2013), has won 71 per cent of his games in the competition (29 out of 41), the second-best ratio after Luis Enrique (73 per cent) among managers to have taken charge of at least 30 games. Besiktas boss Senol Gunes has lost only two of his 18 games as manager in the Champions League (W6 D10).

Chelsea v Barcelona

7 - Chelsea are unbeaten in their last seven Champions League games against Barcelona (W2 D5).

1 - Barcelona have won only one of their six away games against Chelsea in the Champions League (D1 L4), it was in February 2006 (2-1). They have also never kept a clean sheet at Stamford Bridge.

1 - Barcelona have reached the Champions League semi-finals only once in the last four seasons. They had made it to the semis in each of the previous six campaigns.

655 - Lionel Messi has played 655 minutes against Chelsea in the Champions League but has yet to score. Against no other team has he played that many minutes without ever finding the net.

791 - Luis Suarez has failed to score in the last 791 minutes of play in the Champions League, his longest drought in the competition. His last goal dates back to March 2017 against PSG.