AP

MONACO (AP) — Record signing Gonzalo Higuain scored two opportunist goals and veteran goalkeeper Gianluigi Buffon made some crucial saves as Juventus won 2-0 at Monaco to take a commanding lead from the first leg of their Champions League semifinal on Wednesday.

Monaco had scored 146 goals before this game, including three times home and away in the previous two knockout rounds. But Juventus gave a masterclass in how to withstand pressure and then punish on the counter attack, with both of Higuain's goals coming after good Monaco spells.

"The job is not complete," said Juventus coach Massimiliano Allegri, whose side remains on course for a domestic and European treble. "But this could become an extraordinary season for us."

Higuain pounced in the 29th minute, side-footing home after Dani Alves had latched onto his pass down the right before back-heeling the ball back to the Argentina striker as he sprinted into the area.

Higuain hadn't scored against Barcelona in the quarterfinals, leading some to question his 90 million euros ($98 million) transfer from Napoli — an Italian record. This goal clearly meant a lot as he bounded over the advertising boards to emphatically milk the applause from the traveling fans.

The Juventus bench rose as one after Higuain slid in to turn home a deep cross in the 59th, with the irrepressible Alves again the provider.

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Before this game, Higuain had only scored two goals in 24 games in the knockout stages of the competition. A strangely poor return for such a prolific striker.

"Goals were not coming for me in this competition," Higuain said. "I knew I just had to stay calm and keep working hard."

Prior to his opener, Monaco's 18-year-old striker Kylian Mbappe had forced two smart saves from the 39-year-old Buffon on his 100th Champions League appearance for the club.

Then, moments after the restart, Buffon showed great composure to read Radamel Falcao's shot and smother it, rather than committing too early and giving Monaco's top scorer an opening to wrong-foot him.

Buffon saved his best for the last minute, showing remarkable athleticism to tip over substitute Valere Germain's point-blank header.

"He's still No. 1 in the world," Allegri said. "He is always decisive in the big games."

No wonder center half Giorgio Chiellini rushed over to hug Buffon at the final whistle.

"Gigi was perfect," Chiellini said.

The winner plays either Real Madrid or city rival Atletico, with Real heading into the return leg at Atletico 3-0 up thanks to Cristiano Ronaldo's hat trick on Tuesday.

Monaco's vaunted attack was blunted by a rock-solid defense that has now conceded only two goals in 11 Champions League games.

"They deserved the win," Monaco midfielder Fabinho said. "Still, you can never completely write us off, given our attack."

The sheer speed of Juventus' approach play took Monaco by surprise, prompting coach Leonardo Jardim to frantically gesticulate to his players early to close down their opponents higher up the pitch.

Forward Paulo Dybala's ability to roam between the lines baffled Monaco, opening up space for Alves playing as a marauding right winger.

Mbappe had Monaco's first effort on target, heading straight at Buffon from Nabil Dirar's cross. The two combined again moments later, with Buffon making a smart stop to deny Mbappe as he latched onto a low cross.

The first goal came just moments after Glik went down holding his face, urging his teammates to kick the ball out despite a promising attack building down the left.

It took the momentum away and moments later Glik was no longer rubbing his sore face, but panting for breath as he chased the galloping Alves down the right.

Monaco tore into Juventus after the break, with Buffon diving at the feet of Mbappe minutes after his save from Falcao.

"In every game I want to show that I deserve to play at this level, despite my age," Buffon said. "The day I quit, I want people to be sad about it."

Monaco found little joy through the middle and so opted for speed down the flanks. But the wily Juventus defense often had every angle covered, and Buffon was there when they didn't.

"With two or three chances they scored twice, and from the same number we couldn't," Jardim said. "But that is also down to Buffon. He made two or three incredible saves."

It was a brutal lesson for a young Monaco team rich that is on flair, but was found out by two-time champion Juventus, which lost the 2015 final to Barcelona.

The difference in composure was emphatically highlighted on the second goal.

After defensive midfielder Tiemoue Bakayoko gave possession away carelessly down the right. Alves patiently waited for Higuain to change his initial run to the penalty spot, and lofted over a precise pass that fell perfectly into his path at the back post.

Higuain seemed to know it would land there: the instinct of a top striker.

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