Turin: Juventus midfielder Arturo Vidal smashed home a second-half penalty to earn a 1-0 win at home to Monaco in an absorbing Champions League quarter final first leg on Tuesday, leaving the tie on a knife-edge.

Vidal, who has missed two penalties this season, held his nerve and fired into the roof of the net in the 57th minute after Ricardo Carvalho bundled over Alvaro Morata, who had been sent clear by Andrea Pirlo's lofted through ball.

There was controversy surrounding the decision as television replays suggested that the initial contact by the Portuguese defender may have been just outside the penalty box.

"Seeing the incident, it's outside the area," Monaco defender Andrea Raggi said. "You could argue that it continues inside and it is without doubt a foul. The referee had only a few seconds to decide."

Monaco coach Leonardo Jardim also criticised the penalty.

"The result was created by an incorrect decision by the team (of officials) that referees," he told a news conference. "This result is not a fair reflection of what happened on the field."

Juventus coach Massimiliano Allegri, whose side faced a Monaco team that had conceded only four goals in eight previous games in the competition, had predicted that the match could be boring but it was completely the opposite.

Although Italian champions Juve dominated possession, Monaco were always a threat on the break and forced Gianluigi Buffon into three top-class saves to deny them an away goal ahead of the second leg on April 22.

Carlos Tevez and Vidal missed excellent openings for a jittery Juventus in the first half and the hosts were lucky to reach the break without conceding a goal.

Yannick Ferreira-Carrasco should have given Monaco the lead when he shot weakly at Buffon and the Belgian had another effort turned away. (Reuters)