MELBOURNE (Reuters) - Bernard Tomic ground down Jack Sock 7-6(2) 6-3 3-6 6-4 to level Australia's Davis Cup first round tie with the United States at 1-1 in Melbourne on Friday.
The rangy world number 20 hit back for the hosts after John Isner wrapped up the opening singles against Sam Groth 7-6(2) 6-2 6-2 on a sweltering day at Kooyong Lawn Tennis Club.
Flourishing on the grass court installed specially for the World Group encounter, Tomic was cruising toward a comfortable victory before a lapse of concentration led to an early break in the third set.
World number 24 Sock held firm to take the match into a fourth but also dropped his level in the heat and Tomic captured the decisive break in the ninth game.
The Australian raised three match points with an imperious forehand winner and sealed the contest when Sock clubbed a backhand long.
"Bernie stepped up. It's never easy after going down 1-0," Australia team captain Lleyton Hewitt said courtside.
Isner and Groth's match was a battle of big servers but the 11th-ranked American returned with fury during his emphatic win.
"It was a very, very good performance for me and certainly I've played some matches... where I've struggled on return but I think today I was pretty solid," Isner said.
Groth was named to play the doubles with John Peers against the Bryan brothers in Thursday's draw.
But former world number one Hewitt, who replaced Nick Kyrgios after his withdrawal with a virus, could also play, despite retiring at the Australian Open six weeks ago.
"We'll wait and see... we'll put the best team out there," the 35-year-old said.
Reporting by Ian Ransom; Editing by John O'Brien