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.
"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."
"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.
Ancelotti will also be without forward Jeremy Menez, who trained on Wednesday but was not included in the squad having been labelled "injured".
