Berlin: Liverpool-bound Naby Keita was sent off for the fourth time this season as 10-man RB Leipzig crashed to a shock 3-0 Bundesliga defeat to Mainz on Sunday.

Keita, who will join Liverpool in the summer, was shown a yellow card, then a red in quick succession late on for fouling Mainz scorers Alexandru Maxim and Bote Baku.

“That was completely unnecessary,” Leipzig’s captain Willi Orban fumed about Keita’s dismissal.

The 23-year-old Keita stormed off the pitch and will be suspended for Saturday’s home match against Wolfsburg.

It was the defensive midfielder’s third expulsion for Leipzig in 2017/18.

He was also sent off for Guinea in a World Cup qualifier against Tunisia, the first of two red cards he earned last October before being dismissed in Leipzig’s German Cup defeat to Bayern Munich.

Last August, Liverpool agreed to pay the £48 million (Dh243.12 million) release clause, plus a premium, to allow the 22-year-old to move this summer. However, Leipzig’s form will save the Reds money.

They would have had to pay £59 million had Leipzig reached the Champions League — they are five points behind the top four places with two games left. If they qualify for the Europa League, Liverpool will pay £52.75 million.

This was Leipzig’s fifth game without a win and leaves them sixth in the table, just hanging on to a Europa League berth.

Mainz boosted their survival hopes as Maxim and Baku hit late goals after Pablo de Blasis netted a first-half penalty.

Victory lifted Mainz out of the bottom three and into 14th with a three-point buffer from the relegation places.

“That was unbelievable,” said Baku after his dream debut. “It couldn’t have gone better for me.”

The win does not guarantee Mainz’s survival, but is a big help with matches against Borussia Dortmund and Werder Bremen to come.

Dortmund later squandered the chance to go second when they were held to a 1-1 draw at Werder Bremen.

Marco Reus continued to boost his chances of going to the World Cup with Germany by netting his sixth goal since February after overcoming a serious knee injury.

The winger fired Dortmund ahead with a well-placed shot on 19 minutes.

However, sloppy Dortmund defending allowed Danish midfielder Thomas Delaney to head Bremen level just before half-time.

Borussia wasted two great chances to grab the winner to leapfrog Schalke into second and Bremen goalkeeper Jiri Pavlenka made a string of great saves.

“That was a world-class performance. He deserves great respect,” Reus said after Pavlenka valiantly protected Bremen’s point.

“I certainly hope to be on the plane,” added Reus about his World Cup chances having missed the Brazil 2014 triumph with an ankle injury.