McEwan held his speed to take the win

The Davitamon-Lotto team sprinter burst ahead of a small group in the final 200 metres as they raced in the rain towards the line.

Italy's Paolo Savoldelli finished in the same time as McEwen but retained the overall lead following his victory in Tuesday's prologue.

Former Tour de France winner Jan Ullrich finished out of the top 10.

However he vowed that he would improve and said: "I will go through the pain barrier now. I am optimistic that it will all come together."

McEwen was making a comeback from a broken rib and said: "I've hardly raced in April because I broke a rib in a crash in Belgium but this win shows I'm back on form.

"I had two objectives at the Tour de Romandie - win this stage and work on my fitness for the Giro d'Italia."

The Tour of Romandie, which most of the peloton use as a warm-up for the Giro from May 6 to 28, continues until Sunday.

Result of first stage:

1. Robbie McEwen (Australia / Davitamon - Lotto) 4:10:21"
2. Mirco Lorenzetto (Italy / Milram) same time
3. Daniele Bennati (Italy / Lampre) same time
4. Enrico Gasparotto (Italy / Liquigas) same time
5. Bram de Groot (Netherlands / Rabobank) same time
6. Alberto Ongarato (Italy / Milram) same time
7. Pedro Horrillo (Spain / Rabobank) same time
8. Arnaud Gerard (France / Francaise des Jeux) same time
9. Leonardo Duque (Colombia / Cofidis) same time
10. Fabrizio Guidi (Italy / Phonak) same time

Overall standings after first stage:

1. Paolo Savoldelli (Italy / Discovery Channel) 4:14:48"
2. Alejandro Valverde (Spain / Caisse d'Epargne) same time
3. Bradley McGee (Australia / Francaise des Jeux) +2"
4. Robbie McEwen (Australia / Davitamon - Lotto) same time
5. Laszlo Bodrogi (Hungary / Credit Agricole) +6"
6. Daniele Bennati (Italy / Lampre) +7"
7. Oscar Pereiro (Spain / Caisse d'Epargne) same time
8. Tadej Valjavec (Slovenia / Lampre) +9"
9. Haimar Zubeldia (Spain / Euskaltel) same time
10. Bram de Groot (Netherlands / Rabobank) same time