FOGGIA, Italy, May 20  (Reuters) - Romans Vainsteins of Latvia produced a power finish for his first success in the Giro d'Italia on Thursday after a stuttering start to his professional career.

The Latvian foiled the victory quest of Italian Gabriele Missaglia within a metre of the finish line, averaging more than 41 kph in the 245 kms race from Lauria.

It had no affect on the overall standings which Frenchman Laurent Jalabert still leads by seven seconds from Italian Danilo di Luca, but for Vainsteins victory was further proof that his luck had changed.

Vainstains tried to become a professional four years ago but after twice signing contracts with Italian teams their sponsors pulled out, leaving him on the sidelines.

This year he was snapped up by another Italian squad and promptly showed his worth with stage successes in the Tirreno-Adriatico stage race.

Then his luck ran out again. He was the overall leader in Tirreno-Adriatico when, because of a missing route sign, he and others went off-course into a vineyard and lost his lead.

"I am no longer angry about it," he said after Thursday's victory. "I have shown that I can win in the Giro, but with the right luck in previous years I could have been winning earlier."

His seventh success of the year came after he and Italy's Fabrizio Guidi hunted down Missaglia, who had broken clear in the final 700 metres of the sixth stage which ended almost 45 minutes ahead of the published schedule.

This was because they started 25 minutes earlier and the the race on undulating Calabrian roads to the plains of Apulia was 12 kms shorter than the original 257 kms.

There was a momentary scare for leader Jalabert. He was caught off-guard when the race field split in two over the final 40 kms.

He quickly joined the leading group of some 70 riders who finished more than 2-1/2 minutes clear of 37 riders with the remainder of the 157 starters scattered further back.