Eugene - Justin Gatlin and LaShawn Merritt remained on collision course at the US Olympic track and field trials on Thursday after coasting into the semi-finals of the 200 metres.
Gatlin, who lit up Hayward Field at the weekend by clocking the world's fastest time this year en route to victory in the 100m, jogged in 20.32 seconds behind Ameer Webb at a rainswept Hayward Field.
"I just took my time, made sure I was in the top three; when the rain hits you, just play it smart. Get to the next round, get faster and rise to the occasion," Gatlin told reporters.
The most impressive display of the round came from Merritt, the 2008 Olympics 400m champion who could emulate the legendary Michael Johnson by winning the 400m and 200m in Rio de Janeiro.
Merritt, who set the world's fastest time this year on his way to victory in the 400m on Sunday, has already clocked the world's fastest time in the 200m, a blistering 19.78 seconds in Nassau on June 27.
The 30-year-old booked his place in the semi-finals of the 200m with a time of 20.09 seconds.
Although it was the third quickest time of the first round, Merritt had eased up a good 20 metres from the end and clearly had plenty left in the tank as he crossed in first place.
Afterwards Merritt said the 200m remains uncharted territory for him, with his priority still the 400m.
'A BIT FOREIGN'
"It felt cool," he said. "It's still a bit foreign to me. But I know I'm fast and I'm strong so I figure I can handle it. It wasn't a hard race. It's only half of my race (the 400m). It felt smooth."
Asked about the possibility of attempting to emulate Johnson's 400-200 double at the 1996 Atlanta Games, Merritt replied: "If somebody did it; that means it can be done again. (The 200m) is not really a serious thing for me. I just want to have some fun with it."
Gatlin meanwhile backed Merritt for the double.
"If anyone can do it LaShawn can do it," he said. "I know he's got it in the tank."
In other heats Thursday, the women's 100m hurdles once again showcased the fearsome strength of depth in the event amongst American runners.
American women have dominated the event this season, owning the top 10 fastest times of the year, with rising star Kendra Harrison threatening to break Yordanka Donkova's 28-year-old world record of 12.21 seconds set in 1988.
Harrison, 23, who ran 12.24 seconds on the same track at the Prefontaine Classic in May, posted the second fastest time in qualifying, winning her preliminary in 12.57 seconds.
Brianna Rollins was fastest with a time of 12.56 seconds.
"I felt a little stiff; I'm just glad I made the next round," Harrison said.
In the women's shot put, world indoor champion Michelle Carter confirmed her Olympic berth with a winning throw of 19.59 metres, comfortably clear of Raven Saunders and Felisha Johnson.
The triple jump meanwhile was won by Georgia's Keturah Orji with a leap of 14.32m.
In the day's other final, American record holder Emma Coburn triumphed in an eventful 3000m steeplechase, winning in a time of 9 minutes 17.48 seconds, crossing ahead of Courtney Frerichs and Colleen Quigley.