Janko Tipsarevic is relishing his clash with David Ferrer in the quarter-finals of the US Open, but admits that it is going to be "really, really difficult" to win.

Tipsarevic progressed to the last eight of the competition with a straight-sets victory over Germany's Philipp Kohlschreiber on Wednesday.

"David is an established top-five player, probably way more underestimated and people are not giving him enough credit for the achievements he has made in his career," the Serbian is quoted as saying by Reuters.

"It's going to be a really, really difficult battle, because both of us are groundstroke players and we play well from the back.

"We don't have huge, huge weapons, so I think a guy who is tactically better and mentally stronger is going to be the winner."

Tipsarevic also reflected on his 6-3 7-6(5) 6-2 win against Kohlschreiber in the fourth round at Flushing Meadows.

"I'm extremely happy how I managed to play good on key and important moments in all three sets," said the 28-year-old.

"I think this was the main difference. All three sets were, even though the score doesn't show it, really, really tight.

"But in important moments I guess because of the confidence I have and the way that I have being playing in the last couple months showed that I make the right decisions in the right moments of the match."

Tipsarevic has never reached the semi-finals of a Grand Slam.