Leverkusens players ushered the fans back and some obliged, albeit briefly, with the stands swiftly emptying on the 90-minute mark as tearful fans made their way onto the grass to celebrate with the players.

Leverkusen are now on 79 points - the best tally after 29 games in German league history - and are 16 clear of second-placed Bayern and third-placed Stuttgart.

The Leverkusen bus arrived at the stadium 90 minutes before kick-off, wading through a sea of fans clad in black and red on the way to the 30,000-capacity BayArena.

Normally known as Bismarck Street, fans had stuck temporary signs saying ˜Xabi Alonso Street along the main road in honour of the clubs coach.

Alonso looked ahead to Thursdays Europa League trip to London to face West Ham, making seven changes to his starting XI and benching stars Wirtz, Jeremie Frimpong and Alex Grimaldo, the latter for the first time in the league this season.

Piero Hincapie, Grimaldos replacement, had an early effort at goal saved but it would be the fit-again Boniface, making his first start since mid-December, who put the home side in front.

With 22 minutes gone, Jonas Hofmann was felled in the box by Bremens Julian Malatini, with the referee pointing to the spot after VAR urged him to view the contact again on the monitor.

Boniface stepped up and nervelessly slotted the penalty past a helpless Michael Zetterer to send the home fans into raptures.

Hofmann was almost the provider again shortly before half-time, his pass finding Amine Adli who fired against the crossbar.

Bremen started the second-half strongly but their hopes of spoiling the party were snuffed out on the 60-minute mark, Boniface finding Xhaka who unleashed a long-range rocket before slapping his badge in front of the ecstatic home fans.

Wirtz, who came on at half-time for Adli, replicated Xhakas effort eight minutes later from almost the same spot on the pitch.

Wirtz added another with seven minutes remaining before sealing his hat-trick in the 90th minute as Leverkusen rid themselves of their nearly men tag in style.

Earlier on Sunday, a 36th-minute goal from Ritsu Doan took Freiburg to a 1-0 win at Darmstadt, pushing the last-placed hosts closer to immediate relegation.

Winless since October and with only two victories all year, the loss leaves Darmstadt dead last, eight points from second-last and 13 points from safety with five games remaining. (AFP)