ATHLETICS WORLD CHAMPIONSHIPS
Venue: Olympic Stadium, Berlin Date: 15-23 August
Coverage: Watch the action live and highlights on BBC Two, BBC HD, Red Button, Radio 5 live and the BBC Sport website (video for UK users only)
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Greene has won the praise of Colin Jackson and Michael Johnson
David Greene set a personal best in the 400m hurdles at the World Championships in Berlin to fire into Tuesday's final.
Drawn in lane four of the second semi-final, the 23-year-old Swansea Harrier ran a strong home straight to finish a comfortable second in 48.27 seconds.
"I've booked my place in the final and now anything can happen," said Greene, who has won praise from Colin Jackson, Michael Johnson and Denise Lewis.
"The final on Tuesday is not going to be the one you would have expected."
Greene has had a remarkable breakthrough season since setting his previous personal best of 48.62 in Prague in early June.
This is a whole new ball game for him, he should get a really good lane in the final - anything can happen
"I have never been as nervous as this for a long time and the nerves are making me run faster," said Greene.
His time makes him the third-fastest qualifier behind Bershawn Jackson, who crossed marginally ahead of the Welshman in 48.27, and favourite Kerron Clement, who won the first semi-final in 48.00.
"That was a fantastic performance, I really believe he can go a little bit better than that again," said Wales' hurdling great Colin Jackson after witnessing the fourth-fastest time by a British athlete in the event.
"[David] showed a lot of experience for someone who has never run at this level before, and he's coming back from injury.
"He had a really good lane draw... he's a very smooth, confident hurdler.
"He keeps a good cool head because he can rely on his technique even when he's fatigued.
"This is a whole new ball game for him, he should get a really good lane in the final - anything can happen.
"I think, Kerron Clement is a bit too strong for everybody... but these other guys, they won't be far off silver or bronze, that's for sure."
Michael Johnson added: "[Greene's] confidence is riding high... his day off is key before the final.
"Does he think about the pressure, or does he look at strategy and take advantage of the possibility that lies ahead?"
No excuses, I just wasn't good enough... I've got a lot to work on
Greene's performance followed an impressive 48.76 run in the heat stages on Saturday where he left double Olympic champion Angelo Taylor of the United States trailing.
A foot tendon injury has hampered Greene's progress over the last two seasons and he has shuttled between different coaches, but before Berlin he felt confident that he could challenge for a place in the final.
The Championships have not been so happy for his training partner Rhys Williams, though, who failed to make the semi-finals after finishing fifth in his heat.
"No excuses, I just wasn't good enough," said the 25-year-old from Cardiff. "I was expecting a lot better."
Williams, running in lane eight in the second heat in Berlin, was quickly overhauled by the runners inside him, although he recovered in the home straight to finish in 49.88.
At the time that was enough to qualify as a fastest loser, the top three in each heat going through automatically, but Williams' mark was overhauled in the later heats.
"There's no margin for error [in lane eight], but I just wasn't on the pace and was beaten by better guys, I've got a lot to work on," said Williams.