Backstroke king Matt Welsh hit back at the Victorian swimming championships with two gold medals to atone for his shock weekend defeat by a teenager.

Welsh won the 50m backstroke and 50m butterfly finals at the Melbourne Sports and Aquatic Centre, relegating his weekend conqueror Andrew Lauterstein to third place in both events.

Up-and-coming Victorian Lauterstein, 16, stunned Welsh in Saturday night's 100m backstroke final, but the teenager couldn't match the world champion.

Welsh won the 50m backstroke in a slick 25.79sec - seven-tenths of a second outside his personal best - with NSW swimmer Josh Watson (26.11) and Lauterstein (26.17) filling the minor placings.

The world record holder then backed up with a narrow victory in the 50m butterfly over AIS swimmer Josh Taylor and Lauterstein in 24.85.

The swim was well outside his world mark of 23.43 and well outside the 23.95 set by his main sprint butterfly rival Geoff Huegill at the Queensland championships on Sunday night.

But Welsh admitted he was lucky to finish the race at all after his goggles slipped when he dived into the water.

"I felt the right goggle was a bit loose - it just wasn't quite sitting on my eye," Welsh said.

"Then I dived in and sure enough, my goggles were around my mouth.

"It was just a bit of luck I got there - I couldn't see anything." Michael Klim continued his impressive comeback from two years of shoulder and back problems, qualifying fastest for Tuesday's 100m freestyle final.

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