Paris St Germain coach Thomas Tuchel admits it will be "very difficult" for Neymar to be able to face Manchester United in their Champions League tie because of a foot problem.

The Ligue 1 leaders swept aside Rennes 4-1 at the Parc des Princes on Sunday night, with Edinson Cavani scoring twice.

However, the absence of their Brazilian star was again under the spotlight after Neymar suffered a recurrence of a foot issue in last week's Coupe de France clash with Strasbourg.

According to Le Parisien, X-rays have shown a fracture line on the fifth metatarsal which the Brazil forward had an operation on last year.

Tuchel maintained there had not yet been a full diagnosis, but accepted Neymar would most likely be ruled out of contention for the first leg of their last-16 European tie at Old Trafford on February 12.

"It's going to be very difficult, that is clear," the PSG coach told reporters following Sunday night's win, according to L'Equipe.

"I do not have confirmation of a new diagnosis.

"As I explained yesterday (Saturday), it's too early to talk about a return date.

"We have to wait for the first week, which is very important, and its reaction to treatment. Only after that can we be more precise, but it's going to be very difficult (for the United match). It is not a secret."

PSG have yet to complete the signing of midfielder Leandro Paredes from Zenit St Petersburg.

The PSG coach joked: "I've been waiting for a few days, but he's not here. I looked for him in the showers, in the cloakroom, in the physio room, with the goalkeepers, but he is not there."

Tuchel, though, accepted the clock was ticking on the potential big-money move.

"Everyone told me, 'it is done', but he's not here," the German added at a press conference.

"It's the 27th (of January) and I'm worried. We're running out of time.

"We've been waiting for Leandro for a few days and he's not here. He's not in the locker room and that's the reality."

Unbeaten PSG have two matches in hand on second-placed Lille, who they lead by 13 points.

Rennes had gone into the break on level terms after equalising after 28 minutes through a clever backheel from M'Baye Niang.

However, the visitors were overrun as PSG scored three goals in the space of 11 second-half minutes after the hour mark.

Rennes coach Julien Stephan said afterwards: "We have more than competed, especially in the first half.

"We did not want to suffer in possession and made an excellent first half, both collectively in the use of the ball and defensive in the control of space.

"However, we knew that to get a result here, it was necessary to make a perfect match and a perfect match lasts 90 minutes. Unfortunately, after the hour of play, the two goals conceded were a blow and the regrets come from that."