Scotland's Robbie Renwick stormed to a new 400m freestyle lifetime best at the World Swimming Championships in Rome, but still missed out on a place in the final.

The 21-year-old clocked 3.46.75 minutes under the searing mid-morning sun, and while that was nearly three seconds better than his previous best time, it was only good enough for fifth in his heat.

But Renwick insists he can't be disappointed with his swim.

"I was quietly confident that I could come out a swim a personal best but to take nearly three seconds off it is amazing," said Renwick.

"I prepared well and training has been excellent. It's good to see it paying off but I've still got some work to do to start making finals."

Meanwhile, City of Edinburgh swimmer Kris Gilchrist flattered to deceive in the 100m breaststroke but remains confident it will be a different story when he competes over 200m.

"I knew it would need a sub one minute swim to reach the final but I'm using this as a warm-up for the 200m. I think the difference in people's swimsuits really showed out there."

Elsewhere, Hannah Miley safely booked her place in the 200m individual medley semi final, touching home third in her heat in 2.10.24m.