Benjamin Bourigeaud’s hat-trick sealed a 3-2 victory in the second leg for the French side.
AC Milan held off a stirring comeback by Rennes to book their place in the Europa League last 16.
The Italian side looked to have the job done after last week’s 3-0 first-leg win at the San Siro, but the Ligue 1 outfit gave them a scare on home soil, with Benjamin Bourigeaud’s hat-trick sealing a 3-2 victory in the second leg.
Milan goals from Luka Jovic and Rafael Leao proved pivotal as they secured a 5-3 aggregate win to go into the hat for Friday’s draw.
Rennes knew they would have to make early inroads into their deficit if they were to have any chance of repairing the damage from a harrowing night in Milan last week.
And they enjoyed the dream start as they went ahead in the 10th minute.
Bourigeaud received the ball in the centre of the pitch, took a touch and then drilled a scorching low effort into the bottom corner.
Milan were able to weather the early storm and got a crucial leveller in the 21st minute to restore their three-goal advantage.
Tijjani Reijnders burst forward and teed up Theo Hernandez to send in an inviting cross which an unmarked Jovic powered home with his head.
The hosts came again and thought they had made it 2-1 soon after but Arnaud Kalimuendo’s effort hit Mike Maignan without the Milan goalkeeper knowing too much about it.
The French side did go back in front in the 54th minute when Bourigeaud got his second of the match, converting from the penalty spot after Martin Terrier had been fouled by Simon Kjaer.
But they were again pegged back four minutes later as Milan made it 2-2 thanks to a fine Leao strike, the Portugal international guiding into the corner after a fine solo run.
Bourigeaud claimed the matchball as Rennes took the lead for the third time in the match as he again emphatically scored from the penalty spot after VAR had spotted a foul by Jovic.
That left them with 22 minutes of normal time to try and muster two goals and, although they attacked with intent and bluster they could not forge any real chances.