Tennis: Tomic clinches Davis Cup tie for Australia

Bernard Tomic downed Denis Istomin as Australia defeated Uzbekistan in the Davis Cup on Sunday to advance to September's World Group playoffs.

Tomic sealed victory for Australia in their Asia-Oceania Group One second-round tie on clay in Namangan with an emphatic four-set victory over Istomin to give his team an unassailable 3-1 lead.

The 20-year-old won 4-6, 6-2, 6-2, 6-3 in the fourth rubber after Australia went into the final day leading 2-1.

It was a personal triumph for the top-ranked Australian, who initially planned to skip the tie before patching up his strained relationship with Australian captain Pat Rafter.

The 28-time Davis Cup champions are bidding to return to the competition's top tier for the first time since 2007.

Tomic, ranked 43rd in the world, took advantage of a tiring Istomin, who was playing for the third straight day and spent four hours on court in the Uzbeks' gruelling doubles loss on Saturday.

Istomin, ranked 46th, claimed a tight first set but from there it was all Tomic as he stamped his authority.

"Bernie played some of the best tennis I've seen him play," Rafter told Australian Associated Press.

"To play two great matches in a row now, that was really important for him.

"Everything went perfectly, it's actually ridiculous how it was. I'm very proud of the guys."

Australia had the edge heading into Sunday's final singles after former world number one Lleyton Hewitt and Matthew Ebden won the doubles over Istomin and Farrukh Dustov, 7-5, 6-7 (4/7), 6-4, 3-6, 6-3.

Tomic got Australia off to a winning start by beating Dustov, 7-6 (8/6), 6-4, 6-4 on Friday.