Lee Chong Wei moved to within two wins of regaining the men's singles title at the All-England Open, but was so disappointed with the quality of the success which got him there that he claimed he would forget it.
The world number one from Malaysia was never in difficulties in a 21-17, 21-19 win over Tienh Min Nguyen, the seventh-seeded Vietnamese player, but shook his head at how much he felt his performance fell below its usual very high standards.
There were some moments of exceptional brilliance from Lee, sometimes with agile defence, sometimes with airborne attack, and twice with spectacularly dismissive brushed kills at the net.
However, he appeared oddly distracted at others, notably when he let slip four match points in a row, before concluding a superb attack-defence-attack combination on the fifth with a flying jump smash.
"I made some simple mistakes," he said, shaking his head. "I just have to forget about it and move on."
He will also be unusual. Tanongsak Saensomboonsuk is a qualifier who has worked his way diligently all the way to the semi-finals, scattering some notable opponents along the way.
He squeezed past the sixth-seeded Chinese player Hu Jun in a thriller, then outplayed Sho Sasaki, the top 20 Japanese player, and now proved consistently too good for Tommy Sugiarto, the son of former world champion Icuk Sugiarto, winning 21-17, 21-11.
Despite the emergence of the Thai surprise packet, it is Chen Long who appears to be the biggest threat to Lee, with his great movement and control, and increasing patience and maturity.
Chen won a match full of deft rallies with mesmerising patterns against Kashyap Parupalli, the top ten Indian, who led 13-11 but could make no further headway.
Chen was denied the expected semi-final with his compatriot Chen Jin however, when the former world champion was well beaten 21-7, 21-14 by the Jan Jorgensen, the world number 13.
The unseeded Jorgensen was admirably quick and assertive, but appeared to benefit for the second match in a row from an opponent with less than adequate fitness.
Yesterday, the fourth seeded Sony Dwo Kuncoro retired against him with a bad back; now Chen's movement was so laboured that he lost 15 of the first 18 points and was hardly in contention. At the end the Dane placed his hand on the Chinese player's arm by way of consolation.
Earlier, the former world number one Tine Baun remained on course for a big farewell when she reached the semi-finals of the All-England Open in the last week of her special career.
Baun, the only woman to deny China a singles title in the past decade, was often at her commanding, emotionally intense best as she won 21-7, 21-13 against Lindaweni Fanetri, the world number 19 from Indonesia.
"I am pleased with the finish this is going to give my career," said Baun, who now plays Sung Ji-Hyun, the fifth seeded Korean.
Earlier, the defeat of Wang Shixian, the former All-England champion means that for only the third time in 16 years the sport's most powerful nation will not win the women's singles.
It is also the first time since 1995 that China has not had a semi-finalist in this event.
Wang was beaten by Saina Nehwal, who took a step nearer becoming the first Indian woman ever to win the All-England title after a long drawn-out battle 23-21, 10-21, 21-16 with a former champion.
"I have to handle the pressure of expectations from all the Indian fans and hopefully I am doing that," she said.