Tuchel insists Chelsea record spend 'needed' and reveals when Aubameyang can train

But the German also confirmed key new signing Pierre-Emerick Aubameyang will not be available immediately due to injury.

The Blues brought in both the former Arsenal striker and Denis Zakaria from Juventus on loan during deadline day.

Aubameyang isn't expected to be available for Chelsea yet, though, after the 33-year-old suffered a fractured jaw during a robbery and assault at his home in Spain prior to his move.

"At the moment he cannot train," Tuchel explained ahead of his side's game against West Ham.

"We first have to make sure he gets a mask to protect his jaw and then we can start to try with the mask from next week."

When inevitably asked about his disciplinary problems at Arsenal, Tuchel dismissed the idea that it would be an issue at Chelsea - despite him having an incident with Auba at Dortmund where he managed him previously.

"That was the only incident," he laughed, "It wasn't even about time keeping it was just about a rule that we set between the matches.

"He forgot about the rule and went to go visit his hairdresser. Nothing big. There was never a big issue. He has a bit of a problem with his time, but also he never misses a meeting.

"But to arrive 60 minutes before is sometimes a struggle. Never a major concern. He has a good heart and is a top character and I'm 100 per cent sure he'll fit into our dressing room."

He continued: "Auba is always happy to fight for something and accept the challenge.

"The more challenges he has, the better it is. If he wants to overcome the number nine curse, or he wants to prove someone wrong in London - the more, the better."

The German also confirmed new signing Zakaria would also be unavailable for the game against the Hammers on Saturday.

Meanwhile, Ruben Loftus-Cheek and Reece James are back and available for selection.

Wesley Fofana became football's third most expensive defender when Chelsea signed him on Wednesday for £69.5million.

And Tuchel credited the Blues' new chairman Todd Boehly for getting the deal over the line in his first window since his takeover.

"Todd was relentless on it and we never gave up. We managed to fulfill this transfer," he said, "Wesley is young, fast and very strong in set-pieces, defending and attacking."

When asked on the chairman's spending of £273.5millionthat broke the transfer world record for the highest spend in a single window, Tuchel said: "The players we got are very good players and very good personalities.

"Everything was needed to inspire the group. We made excellent signings. It does not help when we talk about the price too much.

"This is how the market was for us, maybe we weren't in the perfect position to find the right price."

After failing to see out their 1-0 lead against Southampton and losing 2-1, Tuchel expressed that his players need to use the boost they've got from the transfer market to translate on the pitch.

He said: "We need to [toughen up]. We will use the end of the transfer period and the energy and stability when you know who's in the squad and who fights for what.

"We will use this stability we need to influence each other. We can see it today and yesterday, there was not the most intense training because of the matches in the week.

"We had a good training session and now I need to choose a team for tomorrow."