Evergreen Swede Sjostrom comfortably won her heat in 23.91s at the Aspire Dome pool, nearly three-tenths of a second quicker than the US’ second-ranked Kate Douglass (24.19s).

“It was good. I’m happy with that. I felt a bit more tired this morning, but I could still swim a pretty fast race,” the 12-time world champion Sjostrom told Reuters, the morning after securing top seed for the 50m butterfly final.

If all goes to plan, world record holder Sjostrom will add to her record 21 World Championship medals in the butterfly decider later today.

Hafnaoui, who swam a stunning 14:31.54s to win the 1,500m gold at the World Championships in Fukuoka last July, qualified only 17th to miss tomorrow’s final.

The Olympic 400m champion and 800m world champion arrived at Doha looking to sweep the 400m, 800m and 1,500m freestyle titles but did not make a single final in one of the more remarkable flops at the global event in years.

Hafnaoui’s meet raises questions about his preparations for Paris, but he declined to answer any post-race questions.

The 1,500m final promises to be a battle nonetheless, with only a few seconds separating the top qualifiers led by German Florian Wellbrock, the Olympic bronze medallist, who had a time of 14:48.43s.

Tokyo Games runner-up Mykhailo Romanchuk (14:51.83s) is fourth seed.

There are six gold medals up for grabs in a bumper evening programme today, which sees Australia’s 50m freestyle world champion Cameron McEvoy defend his title and American Claire Curzan attempt to complete a rare sweep of the backstroke golds by winning the 200m.

South African veteran Chad le Clos will bid for a medal in the men’s 100m butterfly, while Italian distance queen Simona Quadarella and German Isabel Gose will battle for the women’s 800m freestyle title relinquished by the absent Katie Ledecky.