The American rained down 11 aces in a match in which he fell a double break behind early in the first set to the world number 39 from Finland.

Dent will now play for his third career title against the winner between world No.1 Juan Carlos Ferrero and Croatian sixth seed Ivan Ljubicic.

Dent, who reached the fourth round of the US Open, lifted a crown in February over Andy Roddick in Memphis.

Nieminen, 22, has yet to win a career honour, losing in four finals including against Roger Federer at Munich in May.

Dent had some work to do after slipping badly early on in a match played in front of a near-sellout crowd approaching 10,000. Local fans piled in despite the Friday night loss of national tennis hero Paradorn Srichaphan.

Nieminen got off to a good start as he broke Dent twice for a surprise 3-0 lead before the American collected his thoughts.

The Californian earned one of the breaks straight back, winning his first game under the roof of the Impact arena on a stormy afternoon.

Nieminen, whose other two semifinal appearances this season have come in Milan and Munich, dropped serve for the second time in the tenth game, putting a backhand long as the persistent Dent level-pegged the proceedings.

The chunky American kept up the pressure with a love game, as Nieminen compounded his own problems with a double-fault trailing 5-6 which gave Dent a set point.

The Finn saved that one and produced a drop volley to bring on a tie-breaker. Dent took charge 5-3, aced again for a set point and won the set after 41 minutes.

Nieminen tried to put his frustration aside and start afresh in the second, but the tactic was of little use. He failed to break in a combative sixth game as Dent saved six break points.

After that watershed, another break of serve for the Dent sealed the victory.

On Friday, Paradorn Srichaphan left a home crowd in shock as he lost in the quarterfinals despite holding a one-set margin over Ljubicic.

A sellout of 9,000 mainly local supporters witnessed their hero's crash as he lost 4-6, 7-6, 7-5 to the sixth seeded European.

Paradorn was close to tears in defeat, burying his head in his towel for five minutes at his chair after losing in two hours, five minutes.

The Asian ace, who has built tennis in the country into a major sport in the space of just a few seasons with his improving performances on the ATP world stage, couldn't believe how badly he had crashed back to earth at home.

"This was a very disappointing loss, I really expected to at least reach the semifinals here. But this was my first time at home," he said after the match.