Britain's Laura Muir was untroubled on her way to Friday's Olympic final of the 1500m, as she comfortably finished second in her semi-final behind Sifan Hassan.
The European champion was leading heading into the home straight but eased off to finish second in 4:00.73, as her Dutch rival came through to win the heat.
Hassan, who is targeting a never-done-before triple of 1500m, 5000m and 10,000m gold, raced through to make sure she finished first. She is already a third of the way there having won the 5000m.
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The first semi was rapid, as the top five all ran inside four minutes, with reigning champion Faith Kipyegon clocking 3:56:80 in first ahead of Ethiopia’s Freweyni Gebreezibeher and Canada’s Gabriela Debues-Stafford.
Katie Snowden was unable to make it through, finishing in a respectable ninth in 4:02.93, just off the personal best she set in the heats.
"The rounds are more never racking than the final, you want to get there, you always talk about the final but you've got to get there first. Olympic final's always going to be really hard to make," Muir told Eurosport.
"Really, really pleased with that, I saw the first semi and saw it was fast so, fastest loser was going to be hard to come by so just wanted to be automatic.
You just want to do it as evenly as possible, I think the paces were even, which is good you don't want a really big burn up for the last lap, I felt really good at the end. I was surprised how fast I was actually considering how I felt.
"I came here wanting to win a medal, I'm going to give it my best shot."
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Jodie Williams recorded a personal best to make the final of the women's 400m, crossing the line in 49.97 - the sixth fastest time in the UK all-time list. She came second in a race won by the Bahamas' reigning Olympic champion Shaunae Miller-Uibo.
2015 world gold medallist Allyson Felix, at her fourth Games having become a mum in 2018, was second in her semi in a season best 49.89 behind Jamaica's Shephenie Ann McPherson, who was fastest through in 49.34.
The Dominican Republic's Marileidy Paulino won the other semi in an impressive 49.38 ahead of Jamaica's Candice McLeod.
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