BIRMINGHAM - US track sensation Christian Coleman cruised into the semi-finals of the world indoor 60m on Saturday as he looks to become the first sprint phenomenon of the post-Usain Bolt era.

Coleman arrived in Birmingham, England, fresh from having set a new world indoor record for the 60m, blasting to victory in an altitude-assisted 6.34sec at the US championships in Albuquerque last month. And the 21-year-old American took his first steps in the global arena in the absence of the now-retired Bolt, whom he beat to bronze in the 100m at last year's London world outdoor championships.

Coleman clocked 6.71sec to win his heat, overcoming a little stumble out of the blocks that left him scrabbling low before he got into his running and put some daylight between himself and the rest of the field.

"I just wanted to come out here and make it to the next round. My start was decent, but I tripped. But I stayed calm and made it through," said Coleman. "My focus is to win. I have come out here to compete and to see if I can come out with the victory. I put a lot of focus on it. I'm really excited and feel well prepared. The crowd here is great so far and I think it will be electric this evening."

Finishing in the third automatic qualifying spot in the heat was Kim Collins of St Kitts and Nevis, who turns 42 next month and is the first athlete over 40 to break the mythical sub-10sec barrier over 100m. The veteran admitted he is looking for one last hurrah to bring the curtain down on an amazing career.

Collins competed in Birmingham when the city first hosted the world indoors back in 2003, winning silver with 6.53, slower than his career best time of 6.47 set in 2015. He also won silver in Valencia in 2008 and finished eighth in Portland two years ago.

"I feel young but it is time to say goodbye" after these championships, said Collins, who made his Olympic debut at the Atlanta Games in 1996 and whose career peaked when he won the 100m world outdoor title in Paris in 2003. "This is it. I can't do it anymore. The body isn't able to do what it is supposed to do. But I am going out in peace -- no low notes, no high notes. There will be no comebacks. I keep telling the youngsters that I am old enough to be their father and that they should show me respect. But it is good with all these young people coming in. As I am going out of the door, I am welcoming them in. I am happy to have done this for so many years."

One athlete thrilled to have been drawn alongside Collins and Coleman was Malta's Jacob El Aida, just 17. "I was over the moon when I saw the draw. I saw the list of heats when I was in the stands and I didn't stop smiling for 30 minutes," El Aida said. "In the call room, I was very nervous and I wasn't sure whether to talk to anybody or whether the others did not want to be interrupted. It helped me that Kim Collins was joking around. I hope I am running when I am 41."

Coleman's US teammate Ronnie Baker topped heat times in 6.57sec, while a host of favourites including Chinese pair Bingtian Su and Zhenye Xie, Briton Chijindu Ujah, Ivorian Ben Youssef Meite and Jamaican-born Turk Emre Zafer Barnes all qualified easily for the semis slated for 7:11pm (1911 GMT) with the final scheduled two hours after that. Two athletes who are also world outdoor champions defended their world indoor titles in morning finals at the Arena Birmingham. First up was Venezuela's Yulimar Rojas, who went out to a best of 14.83m in the triple jump, Jamaican Kimberly Williams (14.48m) taking silver and Spain's Ana Peleteiro bronze (14.40).

And then New Zealand's Tomas Walsh smashed his indoor personal best with a championships record of 22.31m to dominate the shot put. Germany's David Storl edged out Czech Tomas Stanek for silver with 21.44.