Christian Pulisic prepares for Frank Lampard's intense training sessions in Chelsea

Christian Pulisic is already preparing for Frank Lampard's intense training sessions in Chelsea by working on his own fitness during his holidays.

The 20-year-old was signed by Chelsea in the January transfer period for £ 58m, but remained on loan at Borussia Dortmund for the remainder of the season.

Pulisic was a key member of the US team that reached the Gold Cup final earlier this month, although he could not avoid a loss to Mexico.

The winger impressed during the tournament and enjoyed a long break before joining his new Chelsea teammates.

But Pulisic tries to get to work and in his free time, he always trains with his father, Mark.

Pulisic and Willian should join the rest of the Chelsea team in Japan, where they will play pre-season games against Kawasaki Frontale and Barcelona.

Lampard, meanwhile, has shown great intensity in his first sessions as a Chelsea manager.

And Willy Caballero was impressed by the impact of Lampard.

"It's great with Frank so far. The way he spoke to us the first day was amazing and so far he has been great, "said Caballero.

"He told us how he wanted us to play, his ideas, how he wanted us to train, and how much work we had to do to succeed.

"He explained what it means to play for Chelsea and we are all delighted to work under him.

"He has played for a long time in this club and has won many trophies, and he wants the same for us as players and for him as head coach.

"We have to be willing to work hard," he told us, "and we have a lot of talent on the team, it's an exciting time to be at the club."