Dominic Thiem has seen off a spirited challenge by Alex de Minaur to seal victory for Austria over Australia in the Davis Cup play-off tie in Graz.

The world No.8 beat the 19-year-old, who is ranked 30 places below him, 6-4 6-2 3-6 6-4 in just under three hours to give his nation an unassailable 3-1 lead.

Thiem, who reached the French Open final earlier this year and ended Rafael Nadal's 51-week unbeaten streak on clay in May, fought back from 3-1 down to take the opening set and then ominously raced into a 4-0 lead on his way to winning the second.

But de Minaur, showing the battling qualities that have become his trademark, responded magnificently to stun the 6,000-strong home crowd by claiming the third set. As the Aussie teen's mentor, and Australia's Davis Cup captain, Lleyton Hewitt was vocal in his encouragment on the sidelines, and visibly delight by the efforts of his young charge.

Thiem threatened to take control of the tie early in the fourth set, but de Minaur saved two break points to level at 1-1 with a gutsy drop shot.