Elena Dementieva believes there is still room for improvement despite continuing to build on an excellent season.

Dementieva has won 11 consecutive matches and she came into the hardcourt major fresh off winning the gold medal in the singles event at the Beijing Olympics.

"I feel really comfortable," said Dementieva, who finds herself two victories shy of capturing the first Grand Slam title of her career.

"But I realise that I need to improve. I need to play better at my next match. Every win gives you a lot of confidence and you just want to continue to play like that."

Dementieva's semi-final foe will be second-seeded Serbian Jelena Jankovic, who recorded a 6-1 6-4 triumph over number 29 seed Sybille Bammer of Austria in the late match.

"I'm very excited to be in the semi, but I'm sure I need to improve my game and play a better match if I want to go to the final," added the 26-year-old.

Dementieva is trying to join Steffi Graf (1988) and Venus Williams (2000) as the only players to capture an Olympic gold medal and the US Open in the same year.

The fifth-seeded Russian has not contested a Grand Slam final since finishing runner-up at the US Open in 2004.

Dementieva has yet to drop a set here and could have dispatched Schnyder in even quicker time but converted just five of 13 break points.

Though Schnyder challenged early in second set, she was never able to gain much momentum, winning just 55 percent of her first-serve points and committing 29 unforced errors.

The veteran, appearing in her 50th major, was attempting to reach her second Grand Slam semi-final having achieved the feat at the Australian Open in 2004.

Jankovic, the highest-ranked player left in the tournament, reached the semi-finals at a major for the third time this year.

Jankovic did receive a slight scare in the quarter-finals but she still pulled out a 3-6 6-2 6-1 victory over number 21 Caroline Wozniacki of Denmark.

The 28-year-old Bammer was in uncharted territory, having never made it to the quarter-finals of a Grand Slam, and she didn't last long against Jankovic.

One of three mothers on the WTA Tour, Bammer has only one tournament victory in her career, claiming a Tier IV event in Pattaya City last year.

The quarter-final round on the opposite side of the draw, to be played Wednesday, is highlighted by the sibling rivalry between Serena and Venus Williams, seeded fourth and seventh respectively.

Sixth seed Dinara Safina and number 16 Flavia Pennetta will contest the other match.