Australia's Emma McKeon has set a new national record to claim 100m butterfly silver at the world swimming championships in Budapest on Monday.
McKeon - Australia's most decorated Rio swimmer with four medals - clocked 56.18 seconds but could not reel in Sweden's Olympic champion and world record holder Sarah Sjostrom (55.53).
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On the second night of the eight-day titles at Duna Arena, McKeon eclipsed the national mark she shared with Jessicah Schipper's 2009 supersuit time (56.23) in the 100m butterfly final.
But Sjostrom, still buzzing from shattering Australian Cate Campbell's world 100m freestyle world record on Sunday night, would not be denied.
Sjostrom claimed her fourth 100m butterfly world crown.
"This is the least nervous I have been at a meet, I think it mostly comes down to being happy and enjoying what I am doing," McKeon said.
It was the third straight race in Budapest that McKeon had lowered her 100m butterfly personal best time.
McKeon also collected her second medal of the meet to date.
![Stroke for stroke: Sweden's gold medal winner Sarah Sjostrom,
leads Australia's Emma McKeon and Japan's Runa Imai.](http://web.archive.org./web/20170726092836im_/https://www.fairfaxstatic.com.au/content/dam/images/g/x/h/y/3/7/image.related.articleLeadwide.620x349.gxhy1d.png/1500932029309.jpg)
She was a member of Australia's 4x100m freestyle relay team that claimed silver on Sunday night.
After two days, Australia have a total of three silver to be fifth on the swimming medal tally behind leaders the United States (three gold, two silver, one bronze).
![Sarah Sjostrom of Sweden is congratulated by Emma McKeon.](http://web.archive.org./web/20170726092836im_/https://www.fairfaxstatic.com.au/content/dam/images/g/x/h/y/2/z/image.related.articleLeadwide.620x349.gxhy1d.png/1500932029309.jpg)
In a demanding world titles schedule, McKeon will also contest the blue riband 100m and 200m freestyle events in Hungary plus another two relay events.
Meanwhile, dual defending world champion Emily Seebohm qualified second fastest for Tuesday night's 100m backstroke final.
Seebohm, who is also the 200m backstroke defending champion in Hungary, clocked 58.85 seconds in the semi-finals to trail world No.1 Kylie Masse of Canada (58.18) ahead of the medal race.
Seebohm's 100m backstroke world title defence has been boosted after Olympic champion Katinka Hosszu of Hungary withdrew from the event to concentrate on Monday night's 200m individual medley final.
Three-time Olympic gold medallist Hosszu fell short of her world record but still cruised to her third straight world 200m IM crown in front of her adoring public.
Seebohm's partner and fellow dual world defending champion Mitch Larkin (53.19) qualified sixth fastest for Tuesday night's 100m backstroke final behind pace setter Xu Jiayu of China (52.44).
And Mack Horton notched a personal best one minute, 46.81 seconds but failed to make Tuesday night's 200m freestyle final.
Olympic 400m freestyle champion Horton was 11th fastest after the 200m semis, with Briton Duncan Scott (1:45.16) topping the timesheets.
Horton, who claimed 400m silver on Sunday night, was a surprise 200m competitor at Hungary after upsetting Cameron McEvoy and Kyle Chalmers at April's selection trials.
"I think it came down to inexperience in 200m racing," Horton said of his semi- final finish.
HOW AUSSIES FARED ON DAY TWO OF THE WORLD SWIMMING CHAMPIONSHIPS
* Women's 100m butterfly final
Emma McKeon (56.18 seconds; national record) - silver medal
* Women's 100m backstroke semi-finals
Emily Seebohm (58.85) - qualified second fastest for Tuesday night's final
Holly Barratt (59.95) - qualified 11th, missed final
* Men's 100m backstroke semi-finals
Mitch Larkin (53.19) - qualified sixth fastest for Tuesday night's final
* Men's 200m freestyle semi-finals
Mack Horton (one minute, 46.81 seconds, PB) - qualified 11th, missed final
* Women's 100m breaststroke semi-finals
Taylor McKeown (1:06.93) - qualified ninth fastest, first reserve for Tuesday night's final
Jessica Hansen (1:07.21) - qualified 13th, missed final
AAP