U.S. men's national team manager Gregg Berhalter has compared Christian Pulisic's struggles at Chelsea to the slow starts from Antoine Griezmann and Eden Hazard in La Liga.

Pulisic, 21, signed for Chelsea from Borussia Dortmund for a fee of around €64 million but has only made three Premier League appearances so far this season.

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The forward said he is "very frustrated" with the lack of playing time at Stamford Bridge, but USMNT head coach Berhalter said it is common for players to take time to adapt to a new club.

"There's a lot of pressure that he's under," he said. "He's at a big club. What I really like about where he is right now is that there's a lot of young players.

"There's a manager who is a manager who is used to working with young players, has that philosophy who wants to build this club with this group of talent and he fits perfectly into that mould.

"I think Frank Lampard has been trying to say: the outside stuff is not real, it's really not -- when you analyse the transfer fee, when you analyse who he's replacing, when you analyse he's the only guy they bought.

"And let's not forget that he's not the only player in the world who has had a challenge adapting at the beginning of a move. Look at Griezmann in Barcelona, Hazard in Real Madrid.

"These are top, top players. [Mohamed] Salah and [Kevin] De Bruyne at Chelsea, of course. The list goes on and on. Because he was the only transfer this year, a lot of attention is placed on him."

Hazard, who joined Madrid from Chelsea in the summer, recently said he must produce better performances for the club, whilst Griezmann said he needs time to adapt to his Barcelona teammates after his €120m summer transfer from Atletico Madrid.

Pulisic came off the bench to assist Michy Batshuayi to score the winning goal in Chelsea's 1-0 victory away to Ajax in the Champions League.

Speaking to a news conference ahead of their trip to Burnley on Saturday, Lampard praised the USMNT captain for his impact off the bench.

"The way he has played, he deserved a starting place regularly in the last few weeks -- but so do others," he said. "It's brilliant that he's coming on making an impact. He'll get his starts.

"Christian is getting stronger, he's getting more in the group. Players that come here, some of them you have to give them a bit of time, particularly young players. He's playing well, he's certainly in strong contention."

Meanwhile, Pulisic has urged Sergino Dest to represent the USMNT after the Ajax defender said he always pictured himself playing for the Dutch national team.

Dest, 18, could still pledge his allegiance to either national team but Pulisic wants the teenager to select the USMNT.

"Yeah, definitely, we're definitely hoping that," Pulisic told reporters. "He was with me in the national team at the last camp and it's good to see him again and in the Ajax first team because he's very young. I'm happy for him."