AC Milan vs Tottenham was less eventful, the only goal of the game came inside the first ten minutes as Brahim Diaz converted with a diving header denying Fraser Forster an incredible goal-line save after he parried Theo Hernandez's shot.
In truth the Rossoneri should be taking at least a two-goal lead back to north London as Charles De Ketelaere and Malick Thiaw each missed close range headers in the second half.
Nonetheless, the victory at home and another clean sheet makes it a very memorable evening for the nearly 80,000 fans at San Siro, who have witnessed a home UCL knockout win for the first time since 2013-14.
Milan started brightly and took the lead inside six minutes, as Brahim Diaz got his first Champions League goal of the season. Theo Hernandez beat Romero in the air and charged onto the ball in the box, firing at Forster who made an amazing save to deny Brahim's shot from the rebound, yet he could do nothing but watch as the Spaniard converted with a diving header from close range.
A few minutes later Tottenham threatened for the first time via a free-kick from the left side. Son's cross into area was met by Dier's header, but Ciprian Tatarusanu caught without problems though he could have been in trouble a few yards either side.
A sloppy giveaway inside Milan's half from Alexis Saelemaekers gifted possession to Spurs' right wing-back Emerson Royal, who let fly from 25 yards yet saw his effort sail straight into the arms of Tatarusanu.
Theo Hernandez had gotten the better of Romero for the goal and he gave him the run-around just over five minutes before the break too, surging around the Argentine and getting to the byline before seeing a cut-back cleared in a nick of time.
The final moment of drama before the interval came in the last minute of the first half as Son went through on goal and saw a shot saved by Tatarusanu and then Kane hit the crossbar with the rebound, though the offside flag went up meaning a goal would not have counter.
There was a big moment of controversy in the opening exchanges of the second half as Romero flew into a challenge on Tonali as he attempted to break down the left side and replays suggested it really should have been a red card as the centre-back flew in with excessive force and studs showing, yet a yellow was given.
Milan looked like they might have to bring on third-choice goalkeeper Antonio Mirante when Tatarusanu was bumped after claiming a cross and rolled his ankle in the process, but the Romanian managed to play through the next few minutes of pain.
De Ketelaere had a huge chance to make it 2-0 on the night when Giroud won a header that found De Ketelaere in behind, though his downward header was just about deflected behind for a corner.
Moments later it really should have been a two-goal lead as another perfect cross from Leao on the left was met firmly by the head of Thiaw at the far post yet somehow landed wide as he headed it back across goal from a few yards out.
With five minutes left on the clock another change was made by Pioli, as Tonali came off having been booked with Tommaso Pobega replacing him in midfield.
Spurs remained camped in Milan's half while the Rossoneri aimed to get a second goal on the break, and Leao perhaps should have done better when found in behind by a low cross from Giroud that he couldn't quite trap.
That would be the Portuguese winger's last action of the game as he was withdrawn for Ante Rebic in the first minute of added time. The remaining few minutes of action passed without danger to round off a very organised and professional performance from the Rossoneri.
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