Jamie Murray and Neal Skupski missed four match points in a disappointing second-round loss in the men's doubles at the Australian Open.

The 14th seeds would have had high hopes of going deep into the tournament after reaching the semi-finals of the US Open last summer but they were beaten 4-6 7-6 (5) 7-6 (12) by American pair Steve Johnson and Sam Querrey, who are predominantly singles players.

Murray and Skupski appeared to have the edge throughout but they were unable to hold onto an early break in the third set and then saw three match points disappear at 5-4.

They had one more in the deciding first-to-10-point tie-break but saved six themselves, recovering from 9-5 down only for Querrey to hit an ace on the seventh chance.

Murray said: "Obviously it's disappointing to lose. We were a bit unlucky at the end how it played out but we had chances in that third set.

"We got the break, had game points the next game. I would have felt comfortable we would have probably gone on to serve the match out. But we lost that game then they had something to fight for."

Murray, meanwhile, revealed he was concerned he might fail a drugs test after a visit to Colombia to spend time with his wife Alejandra's family.

The Scot's worry stemmed from a positive test returned by world doubles number one Robert Farah, who blamed contaminated meat from his homeland.

Murray said: "I went to Colombia in December and got tested three days later when I was in Miami. When this news came out I was a bit stressed about what my test would be but I passed it."

News came on the same day just before the Australian Open that Colombian Farah and Chilean top-100 singles player Nicolas Jarry had both failed tests and were serving provisional suspensions.

Both have protested their innocence, and Murray is inclined to believe Farah, who he and Skupski lost to, along with Juan Sebastian Cabal, in New York.

He said: "Obviously it's a shock. It's not every day players are failing drugs tests and there were two in a day that came out.

"For me personally, I don't believe that he especially was taking stuff to influence his performance. He was already number one in the world, he had two grand slams, at that moment why would you start taking something?

"And in doubles you're so reliant on your partner and there's no endurance to our sport except in the grand slams so it doesn't really make sense. I would believe him for the moment but we'll just have to wait and see."

There was better news for Britain's other representatives in the men's doubles.

Skupski's brother Ken, playing with Mexican Santiago Gonzalez, beat second seeds Lukasz Kubot and Marcelo Melo 7-5 7-6 (4) while Joe Salisbury and his American partner Rajeev Ram, who are the 11th seeds, defeated Tennys Sandgren and Jackson Withrow 6-3 6-3.

Scot Jonny O'Mara was already through to the third round with his partner Marcelo Arevalo from El Salvador.