Rami Rennow: #Gatlin, external looking better at the weigh in. #Bolt, external needs to take round one tomorrow. #HeavyWeightContest, external.

Shyan:  Didn't all the commentators say the same things about Bolt not being fit in 2012? Then had to eat their words after the final.

Jo Pavey
European 10,000m champion on BBC TV

"James Dasaolu had a great season last year, and so you'd think he'd know how to perform at a major championships. It's a concern that both he and Richard Kilty didn't know where they were in their races."

Image source, Reuters

On the field, Britain's Steve Lewis has failed with two attempts at 5.55m in the pole vault but he has one more attempt so there's no need to panic - yet. The heptathlon's 200m will start in a minute or so - stand by! 

Daley Thompson
Two-time Olympic decathlon champion on BBC TV

"Dasaolu was running great to 40m, and then it got away. He didn't have the right race plan."

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"James Dasaolu surprised me. He got a very good start, but he stayed too far forward for too long. He gets out of that, but then he shuts it down. I don't understand why an athletes with his times would shut it down so early."

Image source, Reuters

Let's talk about the fastest qualifiers for a bit because Richard Kilty is through to the semi-finals, thanks to that late dip for a 10.12-second run in his heat, but European 100m champion James Dasaolu fails to qualify, which is a slight surprise. 

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"I'm not pleased with this at all. It looks clunky. It's not Usain Bolt. His first 20m has to be better. I think he's holding back a little bit, but things are not there for Usain Bolt."

"I was thinking about the start too much," admits Usain Bolt to Phil Jones. "Overall it was ok, I didn't use too much stress. I'm trying to get business done, that's all."

Steve Cram
BBC athletics commentator

"There's more in the tank for Usain Bolt. He's got a lot to do to match Justin Gatlin, but I wonder if he's just keeping us all guessing there."

Bolt nodding his head as Bob Marley's Is This Love rings out of the sound system before the sprinters are introduced. What form is the defending champion in? 

An iffy start from the Jamaican but he powers through in trademark style. It was comfortable for Bolt in the end, relaxing as he crosses the line ahead of Michael Rodgers in 9.97 seconds. 

Image source, AFP

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"Justin Gatlin has a very unorthodox style. Most athletes want to stay low at the beginning, but he actually bends at the torso. He's all front side. He pulls himself rather than pushing himself. He has that much power."

What has Justin Gatlin to say about his performance? "I've worked really hard for this," he says. "It's not about me, it's about track and field, it' s about the 100m, to come out here and make one of the most exciting races with Usain Bolt - it's an honour."

Decibels rise a little inside the stadium, which must mean Usain Bolt has appeared. How quickly will he go? 

Image source, PA

Colin Jackson
Two-time world 110m hurdles champion

"Justin Gatlin runs like a metronome. Each stride is accurate. Each stride has power. He has an incredible amount of acceleration that pulls him through the field, and that will make him very dangerous."

Justin Gatlin salutes the flag-waving crowd as he's introduced to the folk in the Bird's Nest. The sprinters step forward... away they go...

No problem for Gatlin, no-one's a threat and he finishes in a remarkable 9.83 seconds - in first place, of course.

Colin Jackson
Two-time world 110m hurdles champion

"James Dasaolu worked hard out of the blocks. He got into a good position. He was upright at around the 45-metre mark. He looked comfortable. I'm not sure if he overstrides, but he got caught. His performance is slower than Richard Kilty's."

Dasaolu clocked 10.13, which is slower than Richard Kilty, who is also hoping to claim one of the fastest loser spots. We must all wait to learn who, if either, make the cut. 

The camera cuts to Justin Gatlin. Things are about to become interesting. Very interesting. 

Image source, Getty Images

European 100m champion James Dasaolu pacing up and down his lane. The Briton restless. Jimmy Vicaut, season's best 9.86 seconds, is a threat in this race, but the top three qualify. 

Dasaolu gets the best start, but then looks as if he runs into treacle around the 70m-mark and he's overtaken by Vicaut, who clocks 9.92 seconds, and two others to finish fourth. 

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"Trayvon Bromell is always a great starter. He's one of the bright stars of the future. His technique is flawless. I've gotten to know this kid very well. He's mature for his age. He loves sprinting, and shows that with a superb time."

Image source, Getty Images