West Ham manager Slaven Bilic believes his team's EFL Cup run will provide them with added confidence in the Premier League.
Bilic's men recorded a 2-1 win over Chelsea on Wednesday to reach the quarter-finals, where Manchester United await.
"You never know in a cup. We approached this competition with great ambition, that was obvious. If we play like this, we are capable of progressing," he said, via the club's website.
"This is not only important for the competition but also for the Premier League. It gives you more confidence. We will be a little bit tired on the training ground, but then it's going to be buzzing and from that we will be less tired.
"Now we have most our players back fit, we can do it, as a unit and a team. Now we have three wins on the spin.
"It's always going to be ups and downs but we need to focus like we have done. I'm very optimistic of course."
Goals from Cheikhou Kouyate and Edimilson Fernandes helped West Ham to a 2-0 lead before Gary Cahill's late effort.
"He is very young and he's relatively unknown in England. I would be lying if I said I expected him to break into the side so quickly," he said.
"He presents himself very well in training and he is a very talented player who needs to keep working hard.
"He has got everything; stamina, he has got technique and skill and a good football brain and he should bring us a lot of qualities."
