Bruno Alves v Nicolas Anelka
Alves has the qualities to frustrate a Chelsea attack which will revolve around Anelka and Didier Drogba, although Drogba has only just recovered from a chest injury and may start on the bench.
Anelka will need all his skills to overcome Alves, who proved an able adversary in the first match at Stamford Bridge but was unable to stop Anelka scoring the only goal. Porto's captain keeps his defence well organised and will ensure that Anelka knows he is in a game thanks to his tough tackling and power in the air.
Raul Meireles v Michael Ballack
In the absence of Frank Lampard, Chelsea will rely on Ballack to play a more defensive role against Meireles. The 26-year-old Portuguese midfielder, Porto's vice-captain, is expected to be his side's playmaker.
Ballack has immense experience at European and national level and while Meireles has the passing ability to hurt Chelsea, it is the German captain's work rate that will be the key to this particular battle. Ballack will need to suppress Meireles, who boasts a range of passes and is not afraid to try his luck from long range.
John Terry v Hulk
Brazilian Hulk was kept very quiet by the England captain in the game at Stamford Bridge. Voted one of the rising stars in the European game last season after some superb performances in the Champions League, Hulk formed an attacking trio with Lisandro Lopez and Cristian Rodriquez. His real name is Givanildo Vieira de Souza but he got his nickname due to a resemblance to the actor who played the comic book hero.
His strength and stocky build allow him to live up to that moniker but it his speed, acceleration and shooting ability will give Terry and the Chelsea defence much to think about. Terry will require all his vast experience to cope with Hulk's trickery.
