Alexei Popyrin has been knocked out in the first round of the ATP Tour event in Rotterdam while his fellow Australian Jordan Thompson won in Dallas.

Australia's Alexei Popyrin has been knocked out of the Rotterdam ATP Tour event in the first round while Jordan Thompson celebrated a more positive result in the United States.

World No.66 Popyrin had his chances against Karen Khachanov but ultimately the Russian prevailed 7-6 (7-4) 1-6 6-7 (6-8) in a three-and a-half-hour epic.

Popyrin won the first set in 64 minutes, having fought back from a late break of serve down.

Khachanov dominated the second set with two breaks of serve to storm to a 5-0 advantage before the deciding set became a battle of wills.

Popyrin was unable to convert a match point on the Khachanov serve in the 10th game and was twice up a mini-break in the tiebreaker.

However, 28th-ranked Khachanov held his nerve to close out the match on his second opportunity.

Popyrin served twice as many aces (10) as his opponent but was only able to break the Khachanov's serve once.

His defeat leaves Alex de Minaur as the only Australian left in the draw.

Others to reach the second round in the Netherlands were defending champion Andrey Rublev and top seed Stefanos Tsitsipas but seeded duo Denis Shapovalov and Aslan Karatsev were among the casualties.

At the inaugural Dallas Open, world No.83 Thompson eased past Spanish veteran Feliciano Lopez 7-5 6-3.

One break of serve in each set was enough for the Australian, who will face John Millman's conqueror Brandon Nakashima in the second round.