Great Britain's Zharnel Hughes admits he has work to do to win a World Championships medal as Christian Coleman underlined his favourite tag.
American Coleman is expected to take the 100m title in Doha on Saturday and sent out a warning in the heats.
He was the only man to go under 10 seconds on the opening day on Friday, winning the final heat in 9.98 seconds.
European champion Hughes, who was joined in the semi-finals by GB team-mates Adam Gemili and Ojie Edoburun, clocked 10.08 seconds.
He said: "I'm happy I got through, that's the main aim and that's what I came here to do – get through the rounds and onto the semi-finals. I'm feeling well. As long as I get it together I know I'll be fine.
"I know the start wasn't that amazing. I'll work on it. I have to find my setting on that block because it's a bit different from what I'm using. Once I find it, I'll be fine."
Four-time Olympic champion Johnson believes Coleman has forfeited his right to become the next face of athletics because of the controversy over his missed tests.
Lord Coe said: "I don't agree with that (from Johnson). It's important we take the whereabouts extremely seriously, and athletes understand it's a part of the ecosystem.
"Most athletes have a network of support around them to remind them so one missed whereabouts should ring serious alarm bells.
"The decision that WADA and the United Anti-Doping Agency took, to review those regulations and to make sure there's no anomalies, I am glad they reviewed that.
"It's a grown-up sensible approach, I am pleased Coleman is here and I want to make sure he is given every opportunity to be one of the faces of these Championships.
"We have to be very careful not to play fast and loose with the reputation of athletes."
It was a low-key start to the Championships with 11,804 fans watching the first session. The capacity of the stadium is 40,000 but it has been reduced for the athletics.
Dina Asher-Smith starts her bid for treble glory in the 100m heats on Saturday afternoon with Daryll Neita, Asha Philip and Imani Lansiquot also hoping to reach Sunday's semi-finals.
