Both players trained fully under returning coach Tito Vilanova the morning after Saturday's draw with Celta Vigo, following recent hamstring problems.
Vilanova himself recently returned to the club following chemotherapy, though his assistant Jordi Roura - who has led the team in his absence - took care of today's pre-match press briefing.
And where Alba and Xavi are concerned, Roura told reporters: "We will decide on day of the match whether they can play, but they are progressing well."
Eric Abidal is also in the squad, having returned as an unused substitute against Celta after over a year out following a liver transplant, but Pedro is suspended and Adriano misses out.
Barca only reached this stage of the competition after a stirring second-leg comeback against AC Milan in the previous round, winning 4-0 having lost the first leg 2-0 in the San Siro.
Roura feels they will have learnt from their experience in Italy and said: "Milan are a very big team and tomorrow will be exactly the same. Paris have big players like (Zlatan) Ibrahimovic, (Ezequiel) Lavezzi, (Javier) Pastore and Lucas Moura.
"Our experience against Milan taught us we must be at 100 per cent and play at a high intensity if we are to win."
Ibrahimovic will be available after a two-match European ban for his dismissal in the first leg of their last-16 clash with Valencia was halved on appeal.
The Sweden striker said: "I would have been disappointed, it's a game everyone wants to play in.
"I thought the red card was a hard judgement from the referee and when I got two games, that was even harder, but afterwards we appealed and took one game away and I became very happy."
Ibrahimovic admits his side will come up against the best team and, in Lionel Messi, the best player in the world today - and possibly, in each case, the greatest ever.
"Today, for sure Leo Messi's the best player," he said. "Maybe they should put the name Messi on the Golden Ball, he has a couple of years more to win it.
"As an active player, it's difficult to say he's the best who's ever played football. Messi has to quit football, then you can decide if he's the best or not.
"It will be a difficult game, they are probably the best team today and probably the best team ever playing football on this planet.
"It will be very exciting to try to find how to play, how to disturb them. Milan played a good tactical game and disturbed Barcelona in their game."
Ibrahimovic's availability leaves Thiago Motta as PSG's only absentee.
Former England captain David Beckham will be available and Ibrahimovic feels he has a major part to play.
"He has big quality and he's a fighter, he has a big heart," said the Swede.
"With two months left, we are still playing for so many competitions and that's where he becomes so important, not all our players have this experience of winning trophies."