Thursday's victories at Romania's FCSB and against Sweden's Elfsborg, respectively, will relieve some pressure on Manchester United manager Ruben Amorim and his Spurs counterpart Ange Postecoglou.
United failed to break through in the first half but Diogo Dalot slotted home at the far post on the hour after Alejandro Garnacho was denied by the outside post shortly after coming on at the break. Kobbie Mainoo then clinched the 2-0 win in the 68th minute.
Spurs fans also had to wait for the second half to celebrate before Postecoglou got his substitutions spot on.
Dane Scarlett headed home in the 70th and then set up fellow youngster Damola Ajayi in the 84th. Mikey Moore wrapped up the 3-0 success as their academy graduates shone.
United finished the league stage unbeaten in third behind Italy's Lazio and Athletic Bilbao of Spain, and ahead of Spurs.
Diogo Dalot scored the opening goal for Manchester United against FCSB. (AP PHOTO)
Lazio were the only team to be assured of a last-16 spot before Thursday, and could afford a 1-0 defeat at Portugal's Braga, who were eliminated despite Ricardo Horta's early winner.
Eintracht Frankfurt, Olympique Lyon, Greek side Olympiacos and Scotland's Rangers also avoided an extra play-off tie.
The 2022 winners Frankfurt lost 2-0 at Roma from Angelina's volley and substitute Eldor Shomurodov, with the hosts clinching a berth in the play-offs which are drawn on Friday and played February 13 and 20.
Like FCSB, Belgium's Anderlecht crashed out of the top eight and must go through the play-offs after losing 4-3 at home against Germany's Hoffenheim, for whom victory came too late to avoid elimination.
Jose Mourinho's Fenerbahce got the last play-off berth, one goal better than Braga, with a 2-2 draw at Denmark's Midtjylland, with veteran striker Edin Dzeko setting up the first from Youssef En-Nesyri and scoring the second himself.
Ajax beat Galatasaray 2-1 as both reached the play-offs, and so did Porto thanks to a 1-0 at Maccabi Tel Aviv, while Twente defeated Besiktas 1-0 to advance and eliminate the Istanbul side.
31°C