Manchester City all but secured a top-four place by beating West Bromwich Albion 3-1 at the Etihad Stadium in their English Premier League tie on Tuesday.
City climb to third in the Premier League, two points above Liverpool and three points clear of Arsenal, with only the teams finishing third and fourth assured to join Chelsea and Tottenham Hotspur in the Champions League.
Arsene Wenger's Arsenal must win their final game at home to Everton on Sunday and hope Liverpool slip up at home to relegated Middlesbrough if they are to guarantee a 20th successive season of Champions League football.
As well as their points advantage over Arsenal, Jurgen Klopp's Liverpool also have a superior goal difference (+33 to +30).
A point at Watford on Sunday will guarantee a top-four place for Pep Guardiola's City, but they can secure third place — and, crucially, avoid the Champions League play-off round — if they win.
City manager Guardiola is now within touching distance of securing his minimum objective of Champions League qualification following a straightforward home win over West Brom.
After Aleksandar Kolarov's free-kick was pushed behind by visiting goalkeeper Ben Foster and Leroy Sane had dragged wide, City went ahead in the 27th minute with a fine team goal.
Sergio Aguero's artful back-heel released De Bruyne, whose deflected cross from the left was tapped in by Gabriel Jesus.
De Bruyne doubled City's lead within two minutes when he shaped a half-volley inside the right-hand post from the edge of the box.
Yaya Toure added a third shortly before the hour, exchanging passes with Aguero, driving into the box and slotting home.
Guardiola used the final half hour to offer Pablo Zabaleta a farewell appearance in City's colours.
The popular Argentine right-back, who has been at the Etihad for nine years, is due to leave the club at the end of the season.
Substitute Hal-Robson Kanu claimed a consolation goal for West Brom with three minutes remaining.