Herta was chased hard in the closing laps

The American finished less than a car length ahead of his Andretti Green Racing colleague to pick up his first victory since 2003.

South African Tomas Scheckter was third, with Brazil's Tony Kanaan fourth and American Sam Hornish Jr fifth.

The result increased British driver Wheldon's overall points lead over Hornish to 78 with six races remaining.

Herta started on pole for the third time this season, but his best finish of the year before Sunday's race had been a third place at the Indianapolis 500.

He was dominant in Michigan, leading for 159 of the 200 laps.

"It was Herta's day. It's very good to see him in Victory Lane," said Wheldon.

Scheckter recovered from a drive-through penalty to take third, pushing Herta and Wheldon hard in the final laps.

Average lap speeds hovered at about 210 mph in the first half of the race, but a yellow flag on lap 122, when Ed Carpenter had mechanical problems, slowed the pace.

Helio Castroneves retired on lap 139 when his car caught fire, and there was a four-car crash involving Townsend Bell, Jaques Lazier, Roger Yasukawa and Kosuke Matsuura with about 20 laps left.

Lazier was a last-minute replacement at Ganassi Racing for Englishman Darren Manning, who was sacked last week.