Usain Bolt was at a loss to explain his performance in Ostrava as he confessed to "going through the motions" despite easing to victory.
There is nothing unusual about the famously-relaxed fastest man of all-time not leaving second gear and still winning, but tonight's laboured finish to the 100 metres was not by choice, as is often Bolt's way.
A sluggish start saw him well off the pace at the halfway stage and, even though he sharpened up to win in 10.04, something was not quite right.
He grimaced a stride out from the line and removed his shoes straight after finishing, moving gingerly away after going down on his knees.
The showman did his best to hide any frustrations, high-fiving the crowd before telling them he loved them, but at the post-race press conference, he admitted to being unhappy with his performance - his first plus-10-second run of the year.
"I'll have to go back to the drawing board, talk to the coach," he said.
"It was just a bad day, I have to get past it and look forward to the next one."
On not ducking under the 10-second barrier, he added: "It doesn't bother me but I started (in a) way I don't usually feel so that does bother me a little bit.
"My legs kind of felt dead. I don't know the reason. Hopefully I can figure out what went wrong and I can fix it for the next run. I never felt the power out of my legs. It was going through the motions, really."
With the defence of his Olympic titles closing in, all eyes are on Bolt, with rivals desperate to find a weakness that can be exploited.
Despite concerns about what went wrong tonight, Bolt is not getting too panicked ahead of the London Games.
"Normally when I run I can tell what went wrong. Normally I can. I didn't feel as explosive running from the blocks. My first 40 was really really bad," he said.
"I don't know what my rivals will think about it.
"But it's all about the Olympics. Losing one race, losing two races doesn't matter, it's about getting to the Olympics and doing your best."
Despite the personal inquest into Bolt's victory, it was still a first place and a comfortable one at that.
Great Britain's Dwain Chambers would have given anything to match Bolt's time but, as it is, he has still to meet the Olympic B standard of 10.24.
The 34-year-old, available for London after a change to the rules relating to doping offenders, clocked 10.28 as he wound up a disappointing fifth.
In the other 100m race, Britain's Mark Lewis-Francis won in a time of 10.36.
Three British hurdlers all repeated their already-done trick of meeting the A standard in the 110m hurdles, with Andy Pozzi fourth (13.36), Lawrence Clarke fifth (13.42) and Andy Turner a disappointing sixth (13.48) in a race won by Dexter Faulk.
Richard Davenport was fourth fastest in the 400m hurdles - his 51.54 almost two seconds slower than the winner, Brent LaRue, but a personal best of 5.72m saw fellow Briton Steven Lewis end third in the pole vault.
Oscar Pistorius swapped the Paralympic World Cup in Manchester for the 400m track here, but the South African was a comfortable last in 47.66 secs as American LaShawn Merritt demonstrated his class with a race-winning 45.13.
Among other Britons, Andrew Osagie impressed in the 800m, finishing second to Adam Kszczot in 1.45.24, while Andrew Baddeley was third in the 3,000m.
In the women's events, Jamaica's five-time Olympic medallist Veronica Campbell-Brown was almost half a second quicker than her nearest challenger in the 200m, finishing in 22.38, while Britain's defending Olympic champion Christine Ohuruogu met the A standard in the 400m.
She recorded a time of 51.59 in one of her best runs over the last year, but still came second to Sanya Richards-Ross. GB's Shana Cox was eighth and last.
South African Caster Semenya was second in the 800m, the 2008 Olympic champion edged out by Pamela Jelimo - GB's Marilyn Okoro was fifth while Dawn Hunt did not finish.
National coach Charles van Commenee will have enjoyed seeing Tiffany Porter - his captain at the World Indoors in Turkey - win the 110m hurdles in 12.65, while Perri-Shakes Drayton met the B standard in finishing third in the 400m hurdles.
