Italian champions Juventus were beaten in a poor display, conceding goals at the start of both halves, allowing FC Porto to take a second minute lead from Mehdi Tarami after Bentancur’s under-hit backpass was intercepted.
The Portuguese outfit doubled their advantage seconds into the second 45 with Wilson Manafa slicing through the Juve defence to set up Moussa Marega.
Juve pulled a goal back in the 82nd minute from Federico Chiesa to remain in the tie ahead of the return fixture, but will not be pleased by an ordinary display.
“When you concede a goal after one minute, a strange one at that, it’s natural the players will lose confidence, especially against a side that knows how to clam up in defence,” Pirlo told Sky Sport Italia.
“Porto got the game immediately on the track they wanted. With such a packed fixture list, it’s normal you cant always maintain absolute focus and the right tempo, but it shouldn’t have happened in the Round of 16 of the Champions League.”
The defeat comes only days after Juve lost to Napoli 1-0 in Serie A, leaving them eight points off the pace domestically, mounting pressure on Pirlo in his maiden season in charge.
Elsewhere on Wednesday, Erling Haaland continued his remarkable Champions League goal scoring form with a double in a 3-2 win away to Sevilla.
The big Norwegian, who has been heavily linked with Real Madrid, has now scored 17 goals in 13 games in the Champions League, while he’s also netted 42 times in 42 games for Dortmund.
We were a bit more motivated and had more passion,” Haaland said. “It wasn’t good to concede two goals, but the three away goals are really good for that.
“We had a good plan, Edin Terzic is a good coach. He told me ‘Today will be my game’.”