Bulgarian swimmer Petar Stoychev won the first start of the Marathon Swimming World Cup 2007  round in the Argentinian town of Rosario.

Stoychev crossed the finish in 7:29,30 hours. Competitors had to swim a distance of 57km, Focus Sport agency reported.

For the first time in his career Bulgarian competitor Tihomir Ivanchev ranked third. Ivanchev, 21, ranked seventh in the 2006 world cup.

The young Bulgarian's highest ranking so far has been fourth place.

Stoychev said that the competition was tough and the difference in the finish times of the first three competitors- insignificant.

Damian Blaum from Argentina ranked second, crossing the finish line two seconds after Stoychev. Ivanchev finished only five seconds after the winner.