PGA Tour rookie Sepp Straka shot a five-under-par 66 to take a share of the first-round lead at the Valspar Championship in Florida.

The 25-year-old, the first Austrian to earn a tour card, has missed six of nine cuts so far but five birdies in 10 holes from the fifth saw him card only his eighth sub-70 round this season.

Graemem McDowell carded a level par round of 71, which was three shots better than Waterford’s Seamus Power.

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Ranked 365th in the world, he shared top spot with American Joel Dahmen, whose best finish in three seasons on the tour is joint second at the 2018 John Deere Classic.

Just a shot back are British duo Russell Knox and Luke Donald.

Scotsman Knox had an erratic round with five birdies, two bogeys and a double bogey but the undoubted highlight was an albatross on the 11th where he holed out from 275 yards.

Donald's round was much less dramatic with five birdies spoiled by his only dropped shot at the last.