The Argentine took a bad knock to the face during Barca's 1-0 win in the first leg of their quarter-final in midweek, during a collision with Smalling 30 minutes into the match.
Brazil global David Neres scored on the other side of the break with a superb curling effort.
Max Allegri's side reached the quarter-final thanks to Ronaldo's hat-trick against Atletico Madrid last month and they have the advantage in their tie against Ajax as a result of Ronaldo's away goal.
Ronaldo had not played since injuring his right thigh while on global duty with Portugal last month, but he showed no signs of a problem.
"Mandzukic has a very expensive way of playing, plus we can't forget that those who played in the World Cup Final had a greater burden on their shoulders".
"We could have done better".
Next Tuesday Juventus will host Ajax in the return leg in Turin.
Their spectacular comeback from a 2-1 first-leg home defeat to Real Madrid with a thumping 4-1 win at the Santiago Bernabeu in the previous round showed that the tie is far from over.
"A step forward, but remember Real Madrid", said Italian daily La Repubblica.
"It was a hard game and complicated at times, but we had the clearest chances".
He also confirmed that 19-year-old Moise Kean will return to the starting line up, after his impressive recent goalscoring run. One of Nicolussi and Coccolo could play tomorrow.
He had been largely anonymous but played the ball out to Joao Cancelo on the right and then burst all alone into the centre of the penalty area, where he directed a flying header into the net.
"CR7, Golden Head", headlined Gazzetta Dello Sport and said it was "a new masterpiece" by the 34-year-old who extended his record goal tally to 125, exactly 12 years after his first one in the competition. The Brazilian worldwide capitalised on an error from Joao Cancelo, before curling his effort beyond Wojciech Szczesny.
Ajax kept putting on pressure on the visitors, However, despite some shots from Nicolas Tagliafico and Ziyech, the domination did not lead to goals.
Ajax immediately went in search of a second and Nicolas Tagliafico fired into the side netting while Neres had the ball in the net again but was clearly offside.
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