Bogotá, Bogota, Colombia, 22 July 2015 | AAP

Australians Matthew Ebden and John Millman have lost their first-round matches at the ATP World Tour’s Claro Open in Colombia.

On the hardcourts in Bogota on Tuesday, world No.131 Ebden, a qualifier, went down to Japan’s Tatsuma Ito 1-6 6-3 6-4.

Millman was eliminated by American Alexander Sarkissian 6-3 6-3.

That leaves Bernard Tomic and Sam Groth as the remaining Australians in the tournament.

Tomic is the defending champion and second seed, and after being handed a first-round bye, is due to face the winner between Adrian Menendez-Maceiras and Alejandro Gonzalez.

Groth has made a quick dash to Bogota from Darwin after scoring two pressure Davis Cup wins last Sunday.

At a career-high world ranking of No.64, sixth seed Groth will take on Argentinian Guido Pella in Bogota.