Franklin posted the fifth-fastest time in the 200-meter freestyle at 1 minute, 56.90 seconds. Camille Muffat of France, a silver medallist in this event at last year's London Olympics, was top qualifier at 1:56.53.
Olympic champion Allison Schmitt shockingly failed to qualify for the team that came to Barcelona, leaving Franklin as the top American hope. She was fourth in London, missing a medal by a hundredth of a second.
Now, she's competing in eight events at the worlds, hoping to join Michael Phelps as the only swimmers to claim eight golds in a major international meet.
"When you have to swim each race three times, you really have to be smart about how you swim them," Franklin said. "So I knew the goal for today was to make it back for semifinals."
It was a good morning for the American team after being shut out of gold the previous night.
Tyler Clary led the field in the 200 butterfly, edging Olympic champion Chad le Clos of South Africa. Connor Jaeger posted the fastest time in prelims of the grueling 800 freestyle, just ahead of Sun Yang of China.
Cameron van der Burgh of South Africa topped the prelims for the 50 breaststroke, a non-Olympic event. Christian Sprenger of Australia, who beat van der Burgh for gold in the 100 breast, advanced in fourth.
Franklin already has a gold in the 4x100 free relay and is a big favourite to make it two-for-two in the 100 backstroke during the evening finals. Then, with only a short break, she'll return to the pool for the semifinals of the 200 free.
"I'm really looking forward to it," Franklin said. "Now that I have that race out of the way, I can really focus on my double tonight."
The schedule is more favourable that it was at the Olympics, where the order of events was flip-flopped: the 200 free semifinals came first, then Franklin competed in the 100 back final.
This time, she'll have her most important race first and merely needs to finish in the top eight of the other to earn a shot at another gold.
"It's nice that it's different from London," Franklin said. "I'm really excited for that."
Franklin swam in the next-to-last heat and trailed Katinka Hosszu, who is shaping up to be one of the big stars in Barcelona. The Hungarian already won gold in the 400 individual medley and looks like a serious contender in the 200 free after going 1:56.73 in the prelims.
"Oh my gosh," Franklin said. "All of us were expecting that. She's had an unbelievable year. We knew she was going to come out guns blazing. It was really fun to watch her yesterday and I know it's going to continue."
Clary paced the 200 fly in 1:56.03, looking to make his mark in an event that Phelps dominated for years until le Clos pulled off a shocking upset at the London Games. Clary also won gold at the Olympics, winning the 200 backstroke in another stunner.
"I had a couple of points during the year where I had a serious sitdown with myself and re-evaluated what I'm doing and is this still what I really want to be doing," said Clary, who also has expressed interest in racing cars.
"I kind of liken a post-Olympic year to the same reason why people go to rehab. You just don't go straight from something like the Olympics and all of a sudden go straight down to nothing, as far as emotional excitement, adrenaline, all that stuff. You've kind of got to taper down. Unfortunately, we don't have something that allows us to do that."
Le Clos, who touched in 1:56.21, finds it strange to be viewed as the favourite.
"It's a little nerve-racking. I'm not going to lie," le Clos said. "There's many guys out there who can beat me. But I'm going to fight to the end like I always do."
At least he doesn't have to worry about Phelps, who is retired from swimming — at least for now — and jetted out of Barcelona on Tuesday after watching a couple of nights of swimming as a fan.
"It's fun for a change to see him watching from the stands, like I was watching him for so many years," le Clos said.
Sun, who already cruised to an easy win in the 400 free, eased into the final of the 800 free just 0.09 seconds behind Jaeger's time of 7:49.28. Ryan Cochrane of Canada was third, only 0.30 separating the top three, with Michael McBroom of the United States, Ous Mellouli of Tunisia and Pal Joensen of the Faeroe Islands all less than 2 seconds off the pace.
"I feel good," Sun said. "It's the kind of feeling you always have when you swim in the preliminaries."
He knows he can't take anything for granted, though, after teammate Ye Shiwen struggled to a fourth-place finish in the women's 400 IM, an event she dominated at the Olympics.
"I was surprised," Sun said through a translator. "Maybe after the Olympics she was feeling pressure. I also feel that pressure."
In addition to the 18-year-old Franklin going for gold in the 100 back, the evening finals feature two other teenage stars.
Sixteen-year-old Ruta Meilutyte of Lithuania is a big favourite in the women's 100 breast, the only drama seeming to be whether she can take down the world record again after she broke it in the semifinals. Katie Ledecky of the United States, also 16, could make a run at the world mark in the 1,500 free after winning gold in the 400.
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