Sam Groth keeps Australia alive in Davis Cup

                                      Sam Groth’s serve was pivotal in his victory over Mikhail Kukushkin of Kazakhstan

Big-serving Victorian Sam Groth has kept Australia's Davis Cup hopes alive with a spirited victory over Mikhail Kukushkin in Darwin on Sunday.

Groth won 6-3 7-6 (8-6) 4-6 7-6 (8-6) to level the quarter-final tie at 2-2 ahead of the deciding fifth rubber.

Lleyton Hewitt has received the nod ahead of Thanasi Kokkinakis for the deciding match, with the Davis Cup legend to go head-to-head against world No.115 Aleksandr Nedovyesov.

The winner of the tie will face off against either France or Great Britain in the semi-finals.

Groth combined with Hewitt on Saturday to win the doubles in straight sets.

And the 27-year-old replaced rising star Nick Kyrgios to play the first singles rubber on Sunday.

Kyrgios appeared mentally drained during his shock four-sets loss to Nedovyesov on Friday, with captain Wally Masur opting instead for the more traditional grasscourt style of Groth.

The world No.68 made a fast start by winning the first two sets.

But with the finish line in sight, Groth faltered in the third, dropping serve in the ninth game to let Kukushkin back into the match.

Groth was down a set point in the fourth-set tiebreak, but he dug deep to win the match in just shy of three hours.

"We've still got one more to go," an emotional Groth told host broadcaster the Seven Network.

"This is the most amazing thing I've ever had in tennis. It's unbelievable."

Groth served 29 aces, many of them in clutch situations.

"My serve is something I rely on. It's my biggest strength," he said.