PSG, who won the first leg 2-1 at the Mestalla, have since beaten rivals Olympique Marseille 2-0 in Ligue 1 and in the French Cup but those two wins were sandwiched between a 3-2 defeat at Sochaux and a 1-0 loss at 10-man Stade Reims.
They will miss the suspended Zlatan Ibrahimovic and Marco Verratti but the Brazil centre-half's comeback from injury is a huge boost.
"I will bring a bit of tranquillity," Thiago Silva, whose composure at the heart of the PSG defence has been impressive since he joined from AC Milan during the close season, told a news conference on Tuesday.
The 28-year-old has not played since Jan. 11 when he picked up a thigh injury in a goalless Ligue 1 draw against AC Ajaccio.
"He is a great player, I am happy that he is back in perfect physical shape," coach Carlo Ancelotti added.
"I expect him to use his individual qualities to help improve our game as a team.
"When PSG play as a team, like they did during the first leg, they're dangerous."
Thiago Silva has little doubt that PSG will be more focused than they sometimes have been in the French League.
"The Champions League makes you be 100 percent focused, which is not always the case with Ligue 1," he explained.
David Beckham "could play", Ancelotti said.
The former England captain, who joined on January 31 as a free agent on a five-month deal, has been included in the squad and could replace fellow midfielder Verratti just like he did when PSG took on Marseille in the French Cup last Wednesday.
Ancelotti will also be without forward Jeremy Menez, who trained on Wednesday but was not included in the squad having been labelled "injured".
Ancelotti would not say who would play alongside Ezequiel Lavezzi and deputise for Ibrahimovic, who was sent off in the first leg, although Frenchman Kevin Gameiro is the only proper striker left.
