Chelsea include midfielder Michael Ballack after he recovered from a thigh suffered earlier this month.
Chelsea are still without Ashley Cole (knee), Joe Cole (foot) and Khalid Boulahrouz (shoulder) but have no other fresh injuries to contend with.
Porto welcome back winger Ricardo Quaresma after suspension.
Coach Jesualdo Ferreira is set to revert to a 4-3-3 formation with Argentine strikers Lucho Gonzalez and Lisandro Lopez iin the line-up.
Chelsea (from): Cech, Hilario, Cudicini, Ferreira, Geremi, Diarra, Carvalho, Terry, Bridge, Morais, Obi, Lampard, Makelele, Ballack, Essien, Shevchenko, Drogba, Robben, Kalou, Wright-Phillips.
SCOUTING REPORT ON THE OPPOSITION
Who are they? Champions of Portugal and cup winners for good measure, this is the 10th time in 12 seasons Porto have been in the competition, and the third time in succession.
Recent form: They are still top of the Liga but have only just started firing on all cylinders after the winter break. Going into Christmas they were unbeaten in 13, but in the four matches since they have 50:50 win:loss ratio. After single-goal defeats to Leiria and Amadora they bounced back with a bang and sunk Naval 4-0 at the weekend.
European record: They won the title by beating Monaco in 2004 under the self-styled 'Special One', Jose Mourinho. He refused to celebrate, moved on to Chelsea and Porto's fortunes have since dwindled as the squad broke up.
How did they get here? By winning the bwin Liga.
Ones to watch: Much has changed since Jose Mourinho left Porto, but he will need no second introduction to striker Helder Postiga whom he helped to develop while he was in charge at the Dragao. If the name rings a bell it is because he had a poor spell at Spurs, but now back in his homeland he has twice helped dump England out of major competitions, is banging in the goals and is the club's leading scorer this term. He has been ably supported by Lucho Gonzalez, Lisandro Lopez and the quicksilver Ricardo Quaresma.
Did you know? That quartet have scored 68% of Porto's goals this season, Postiga weighing in with 10, Gonzalez nine, Lopez eight and Quaresma seven. And if Chelsea are to prioritise who to keep quiet they should keep tabs on Argentine duo Gonzalez and Lopez. When they have scored this term, Porto have won.
BIG MATCH STATS
Definitions of terms used:-
Champions League (CL) - only group phase matches and beyond of this competition which began in 1992-93.
Champions Cup/Champions League - all matches played since it began in 1955-56 including qualification matches.
European matches - all matches played in the major European tournaments (Fairs Cup, Uefa Cup, Cup Winners' Cup, Champions Cup, Champions League).
Uefa Super Cups, Intertoto Cups and the old Intercontinental Cup competition are excluded.
Head-to-heads
FC Porto and Chelsea have met each other twice in European history. Both matches were played in the group phase of the 2004-05 Champions League. On 29 September, Chelsea won 3-1 at Stamford Bridge with goals from Smertin, Drogba and Terry for the home side and Benni McCarthy for Porto. In the reverse match on 7 December, Porto won 2-1. Duff gave the English side the lead, but Diego and Benni McCarthy secured victory for the Portuguese.
Porto have a very good record in home matches against clubs from England; unbeaten in all nine meetings (four wins, five draws). Chelsea have never played a club from Portugal in a European match, apart from Porto.
European history
FC Porto won the Champions League in the 2003-04 season, defeating AS Monaco 3-0 in the final. They have also won the Champions Cup (1987), the Uefa Cup (2003), the European Super Cup (1987) and the Intercontinental Cup (1987, 2004) twice. This is their 12th Champions League season, a record jointly held with Manchester United.
Chelsea's biggest success in European competition is winning the Cup Winners' Cup twice (1971 and 1998). They also won the European Super Cup in 1998. This is their fifth CL participation. They have now reached at least the last 16 in each of their four CL campaigns, and were semi-finalists in 2003-04 and 2004-05.
Current European form
Porto are unbeaten in their last five home matches in the Champions League. Their last home defeat came on 28 September 2005 when succumbing 2-3 to Artmedia Bratislava.
Overall, FC Porto have not lost in their last four CL matches. Their last defeat dates back to 26 September 2006 when Arsenal beat them 2-0.
Player and disciplinary info
Joe Cole (Chelsea) will suffer a ban if booked. John Terry (Chelsea) returns after suspension.
Lisandro Lopez and Luis Gonzalez are Porto's top scorers in this competition with four goals. Gonzalez, Bruno Alves, Helton and Pepe are all yet to miss a minute this season. Andriy Shevchenko is the most experienced Chelsea player with 84 CL appearances. He's also the most prolific goalscorer in Chelsea's squad with 44 career CL goals. Michael Essien is the only player to have been on the field for every minute of the Londoners' CL campaign this season.
Other miscellaneous facts
This is the 150th match in Europe's elite club competition, the Champions Cup/Champions League combined, for the Oporto-based club. Their next defeat will be the club's 50th in the history of the Champions Cup/Champions League.
Porto lead the Portuguese League with 43 points from 18 matches, holding a four-point advantage over Benfica. Chelsea are going strong in all four competitions. The Carling Cup finalists and FA Cup quarter-finalists trail Manchester United by six points at the top of the Premiership.
Big Match Stats source: Infostrada Sports
The first leg of the round of sixteen in the  was completed on Wednesday, with at least one controversial result, and a bag full of ties.  The leg began on Tuesday with four games, and the other four were played the next day, including reigning champions FC Barcelona of Spain.

Champions League logo.