Durban - Chad le Clos has won his big showdown with Dylan Bosch on the opening night of the South Africa Aquatic Championships with the pair among four swimmers to post Commonwealth Games qualifying times in Durban on Monday.
Olympic gold medallist Le Clos recorded the fastest time in the world this year to win the 200 metres butterfly final in one minute, 54.56 seconds (1:54.56).
Bosch, who broke the NCAA or American Universities' record in the 200 yards butterfly just under 10 days ago, was second in 1:56.92 with both men dipping under the 1:57.03 qualification mark.
There were also qualifying times posted by Myles Brown in the 400m freestyle final, which he won in 3:49.05, while Karin Prinsloo was the only female to book her ticket to Glasgow 2014 with a time of 1:58.43 in the 200m freestyle.
The Le Clos-Bosch showdown was the most anticipated of the evening as the reigning champion lead a high-quality field from start to finish.
The 21-year-old Le Clos is bidding to win eight individual titles at the meet this week and was delighted by his performance.
"It felt really good," Le Clos said.
"My coach and I spoke about going under 1:55, that's the best time in the world this year, and I'm really happy with that.
"A big ups to Dylan for getting the time as well.
"It will be great to have both of us in the same event at the Commonwealths, both right up there in the top five."
The six-day competition at the Kings Park Aquatics Centre is doubling up as the nationals as well as the official qualification event for the July 23 to August 3 spectacle in Scotland.
Bosch, who was ahead of Sebastien Rousseau (1:58.73), the fastest swimmer in the heats, was pleased with his own showing.
"It's really nice to make it," Bosch said.
"There's a lot of travelling to come all the way from America where I had a hectic schedule over the past month, so it's just really nice to get the time in.
"Now going off to Scotland to represent South Africa, it's what I came here to do and I'm delighted."
In the men's backstroke semi-finals, Gerhard Zandberg (25.27) came in fastest ahead of Ricky Ellis (25.51) and Charl Crous (25.78).
Meanwhile, Prinsloo initially set the tone for the evening by waltzing home less than a third of a second inside the qualifying time of 1:58.74.
The 24-year-old London 2012 Olympian was well ahead of Marlies Ross (2:02.06) and Rene Warnes (2:02.30) and she was delighted afterwards to have secured her place in Glasgow so early in the meet.
"It's always good for your confidence when you start off a competition so well," Prinsloo said.
"There's always pressure coming into these events, so I'm just relieved to have got through."
Ross missed out on 200m individual medley qualification by recording a time of 2:15.83 on her way to winning gold. Her time was less than a second slower than the 2:14.97 qualifying time.
Vanessa Mohr (27.08) was the fastest qualifier in the 50m butterfly, while Tara Nicholas (31.95) secured the top time in the 50m breaststroke semi-finals.
All swimmers must record the stipulated qualifying times this week if they want to have a chance of making the South Africa squad for the Commonwealth Games.
Results from the evening session on day one of the South African Aquatic Championships at Kings Park, in Durban, on Monday:
Men's 50 metres backstroke semi-final 1:
1. Ricky Ellis 25.51
2. Darren Murray 26.17
3. Clayton Jimmie 26.62
Men's 50 metres backstroke semi-final 2:
1. Gerhard Zandberg 25.27
2. Charl Crous 25.78
3. Bryan Gray 26.28
Men's 400 metres freestyle final (Commonwealth Games Qualifying Time 3:49.55):
1. Myles Brown 3:49.05*
2. Brent Szurdoki 3:55.72
3. Calvyn Justus 3:55.75
Men's 200 metres butterfly final (CGQT 1:57.03):
1. Chad le Clos 1:54.56*
2. Dylan Bosch 1:56.92*
3. Sebastien Rousseau 1:58.73
Women's 200 metres individual medley: (CGQT 2:14.97):
1. Marlies Ross 2:15.83
2. Rene Warnes 2:16.48
3. Tatjana Schoenmaker 2:19.86
Women' s 200 metres freestyle final (CGQT 1:58.74):
1. Karin Prinsloo 1:58.43*
2. Marlies Ross 2:02.06
3. Rene Warnes 2:02.30
Women's 50 metres butterfly semi-final 1:
1. Marne Erasmus 27.49
2. Trudi Maree 28.00
3. Tayla Lovemore 28.04
Women's 50 metres butterfly semi-final 2:
1. Vanessa Mohr 27.08
2. Jessica Ashley-Cooper 27.38
3. Rita Naude 28.17
Women's 50 metres breaststroke semi-final 1:
1. Franco Jonker 32.19
2. Tatjana Schoenmaker 32.79
3. Jamie Reynolds 33.00
Women's 50 metres breaststroke semi-final 2:
1. Tara Nicholas 31.95
2. Jusine Macfarlane 32.12
3. Emily Visagie 32.55
*Denotes Commonwealth Games qualifying time