Frank Lampard has admitted he will fight to boost Kepa Arrizabalaga’s brittle confidence after the goalkeeper’s latest mistake in Chelsea’s 2-0 Premier League loss to Liverpool.

Sadio Mane blocked Kepa’s laboured clearance and tapped home his second goal as 10-man Chelsea succumbed to Jurgen Klopp’s defending Premier League champions at Stamford Bridge.

Andreas Christensen’s red card handed Liverpool an advantage they fully exploited, but Blues boss Lampard conceded Kepa was at fault for the second goal – and is in desperate need of a confidence boost.

Lampard revealed veteran Willy Caballero will start Wednesday’s League Cup clash with Barnsley at Stamford Bridge, but insisted that was always the plan, even before Kepa’s latest costly error.

“It’s a clear mistake that has cost us,” said Lampard.

“Because we went on to have a penalty that things could be different if we score, and fine margins like that change games.

“So, we have to keep working, Kepa has to keep working and he has to have support around him, that’s very clear. But it was a clear mistake on the day.

“And now we’ve got to try to give him confidence, because that’s important. It’s a clear mistake, he’s accepted that and we have to hold our hands up to that.

“I can say now that Willy Caballero will play against Barnsley, and that was always my feeling to play him on Wednesday, regardless of today. So I don’t want people to make judgements on that game itself.

“He’s our player and it’s clear now from the two games, today was a clear mistake and there was a mistake at Brighton as well, and he’s reflected on that in that way.

“So we have to keep working, that’s the rules of football, difficult times, individually players need support, particularly from myself and I give that to all the players. So we have to keep working.

“Nobody tries to make mistakes in football, that’s the nature of the game. So we have to be strong and keep going.”

Rennes stopper Edouard Mendy is close to completing a move to Chelsea, but Lampard has upheld his policy of refusing to talk about players from other clubs.

Kepa’s poor form from last term has spilled into the new campaign however, and the £72-million signing in 2018 appears to face a hugely uncertain future at Stamford Bridge.

“I don’t have news on the Mendy one so I’ll stay away from that,” said Lampard. “Until anything’s confirmed you should never speak on other players, so that’s that.”

Liverpool dominated Chelsea once the Blues were reduced to 10 men, with new boy Thiago Alcantara impressing off the bench after replacing Jordan Henderson.

Henderson suffered a knock to his thigh that Klopp does not expect to keep him sidelined for any length of time.

Thiago excelled off the bench in Henderson’s stead though, leaving Klopp to praise the Spain midfielder.

Alisson saved Jorginho’s second-half penalty, ending the Italian’s flawless run of eight successful spot kicks for the Blues, and that left Klopp hailing the ideal west-London afternoon.

“Jordan [Henderson] said he had a knock and I told him not to carry on because we didn’t want to take a risk with him,” said Klopp.

“But then even without training, and albeit against 10 men, Thiago set the perfect play in that position.

“Everything he did was perfectly natural. Alisson saved a penalty, Thiago made his debut – and if Hendo has absolutely nothing to his injury, it’s a perfect day.”