Barcelona came from behind to earn a 1-1 draw with Napoli in the Champions League on Tuesday as Antoine Griezmann netted a vital away goal in the round-of-16 first leg.
The finish saw the Belgium international become the joint-highest scorer in Napoli history with 121 goals -- level with Marek Hamsik.
The home team frustrated Barca for much of the first half, but the visitors equalised on 57 minutes when Nelson Semedo crossed for Griezmann to finish a well-worked move in clinical fashion.
Pique's potenial absence could be especially crucial with Sunday's La Liga Clasico against Real Madrid looming.
"We'll see what problem he has, then we can confirm if he'll be available [against Real Madrid]," said Barcelona coach Quique Setien.
As a result of his sending-off for fouling Mario Rui and then butting heads with the defender, Chile international Vidal will miss the second leg against Napoli at the Camp Nou, as will fellow Barca midfielder Sergio Busquets, who was also booked.
On Vidal's sending off, he added: "I didn't see precisely what happened, but perhaps the referee was a bit harsh.
"A yellow card for the foul is one thing, but the second is too much. There are moments of tension that players who experience the game with his temperament can have."
Napoli goalscorer Mertens' presence in the second leg is also in question after the forward limped off in the second half.
Lionel Messi was making his 141st appearance in the Champions League, taking him joint-fifth on the list for most games played in the competition, alongside Manchester United's Ryan Giggs.
The game -- which was the two sides' first meeting -- also marked the first Champions League knockout fixture in which neither manager had previously coached in the competition.
Napoli coach Gennaro Gattuso was left frustrated at the result after his well-drilled defence largely stifled a quiet Messi and co.
"I think they barely grazed us tonight, they hardly had a single shot on goal," he told Sky Sport Italia.
"They could've been there all night and not scored, but we conceded after one single error. They didn't hurt us, it barely tickled."