Bovell, 29, a bronze medallist in the 200m medley at Athens, clocked a best 21.77sec in the heats to head into Thursday night´s semi-finals the fastest qualifier ahead of Brazilians, world record holder Cesar Cielo and Bruno Fratus.[break]
Bovell, ranked 12th fastest going into the Games, clocked 21.80sec just two-hundredths of a second quicker than Cielo.
Cielo fancies his chances in the 50m helter-skelter after leading at the turn in Wednesday´s 100m freestyle final.
"It was hard to sleep last night ater the race, because the (100m) final was so late," Cielo said. "This morning I was more concerned about making enough of an effort to get back.
"It´s a matter of resting now to make sure I get a spot in the final."
Experienced sprinters Anthony Ervin of the USA and South Africa´s Roland Schoeman were well in the mix with the fourth and fifth quickest times, but it was hard going for Magnussen, who was 10th (22.11sec).
Magnussen was still coming to terms with his shattering loss to American Nathan Adrian in Wednesday´s 100m final by one-hundredth of a second.
"If I am being totally honest, the last thing I wanted to do this morning was get up and swim again," Magnussen said.
"I couldn´t sleep last night, but it´s another day today. I had the chance to sit back and think about what happened.
"I have taken it all a little for granted and last night´s race was an important part of my life, I am going to regroup and hopefully go onto do a few bigger and better things."
Australia´s former 50m world record holder Eamon Sullivan squeezed into the semi-finals in 16th and last spot with 22.27sec.
"I wasn´t planning on that. I lost a bit at the start which is probably the most crucial part of the race," Sullivan said.
"I didn´t start feeling good until yesterday, I needed a few days after the (medal-less 100m freestyle) relay to get my mind back on track, I was a bit shocked.
"I am sure if I get my start right tonight I will be under 22sec."
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