Eilish McColgan ran a personal best and comfortably met the Olympic 5000m qualifying time on her return to the track after a 22-month injury lay-off.
McColgan's time of 15 minutes 09.94 seconds at the Payton Jordan Invitation in California was well inside the 15:24.00 qualifying mark.
"Can't stop smiling," tweeted McColgan, whose time was 35 seconds quicker than her previous best over the distance.
"First track race in over 22 months was worth waiting for!"
The Scottish middle-distance runner suffered complications after surgery on a broken ankle, which robbed her of any competitive action in 2015.
She has now switched disciplines having previously specialised in the 3000m steeplechase. She finished sixth in the final of the 3000m steeplechase at the Commonwealth Games in Glasgow in 2014.
McColgan finished fifth in California behind fellow Scot Laura Whittle, who was fourth in a time 15:08.58.
In the men's 5000m Scotland's Andrew Butchart delivered an impressive run to come in second, his time of 13:18.96 under the 13:25:00 required to meet the qualifying time for Rio.