Chennai: Japan's Go Soeda marked Japanese resurgence with an emphatic straight set win over defending champion Stanislas Warwinka while fellow-qualifier and compatriot Yuichi Sugita nearly emulated the feat but blew three match-points and went down to second seed Nicolas Almagro in two gripping quarter-final matches of the Aircel Chennai Open on Friday.

The unheralded Soeda pulled off the biggest win of his career by knocking out World No.17 and third seed Wawrinka of Switzerland 6-4, 6-4, while Sugita stumbled in the second set tie-break after clinching the first as a rather rusty World No.9 Spaniard Almagro scrambled to a 4-6, 7-6 (8), 6-4 win over two hours and 44 minutes.

In Saturday's semi-finals, Soeda takes on top seed and World No.9 Janko Tipsarevic of Serbia who needed three sets (6-3, 3-6, 6-2) to subdue Belgian wild card David Goffin while Almagro faces fourth seeded Canadian Milos Raonic who put out Isarel's Dudi Sela 7-6 (4), 6-3.

The 27-year-old Soeda, ranked 120, showed tremendous maturity to see off Warwinka who was never quite there and seemed rather distracted and unsettled in a match in which both players struggled to hold serve, especially in the second that saw seven breaks as against one in the first.

'Obviously, I am very happy to have beaten a great player like Warwinka. Having played the qualifying rounds and a couple of tough matches in the main draw, I was a bit tired,' said Soeda.

Wawrinka, surprisingly made to play on an outside court, never looked comfortable in different conditions as opposed to the Centre Court where he had played the previous round.

'I didn't deserve to win today. He played much better. The first tournament of the year is always difficult. It happens that when you are not playing well, the guy on the other side of the net is better. But that's tennis,' said Wawrinka.

The 20-year-old Raonic, winner of ATP's Newcomer of the Year award in 2011 in recognition of his meteoric progress through the rankings from 152 to 25 before finishing at 31 following hip surgery, did just enough to get past Sela.

The 26-year-old Sela, ranked 83, squandered chances in the second set when he was in full flow with delicate placements and precision shots to the corners while putting up a dogged resistance, especially in the closing stages of the match.

'I am happy with the result today. A lot of things went right for me, but there are a lot of things I have to address for tomorrow. I served better than in the
previous round, but was hesitating a lot on what shots to play when I had the options. I never really got a grasp of it,' said Raonic.

Almagro, woefully short of match practice and fitness, was certainly lucky to survive Sugita's challenge that was perhaps much greater than the Spaniard expected, given the obvious difference in class and rankings.

After dropping the first set, Almagro managed to stay with Sugita until the tie-break where the Japanese had three match points, but the Spaniard saved them with a series of blistering winners that had the stamp of class to take the match into the third set.

In the decider, Sugita was running on an empty tank and the tough battles over the week seemed to tell on him and Almagro quickly seized the opportunity to race to victory.

The results (quarter-finals):

1-Janko Tipsarevic (SRB) bt David Goffin (BEL) 6-2, 3-6, 6-2; 4-Milos Raonic (CAN) bt Dudi Sela (ISR) 7-6 (4), 6-3; Q-Go Soeda (JPN) bt 3-Stanislas Wawrinka (SUI) 6-4, 6-4; 2-Nicolas Almagro (ESP) bt Q-Yuichi Sugita (JPN) 4-6, 7-6 (8), 6-4.