Top seeds Serbia shrugged off Jelena Jankovic's ongoing injury in Perth on Thursday to clinch a Hopman Cup final showdown with United States.

Serbia beat Argentina 2-1 to finish top of Group A while the US, led by Serena Williams [Images], whitewashed hosts Australia 3-0 to win Group B.

World number three Jankovic, who hurt her right leg on Wednesday, could not complete her singles match with Gisela Dulko as Argentina went 1-0 up against the Serbs.

Novak Djokovic, the men's world number three, levelled the contest with a 6-2, 6-3 victory over Juan Ignacio Chela before Jankovic returned to help Serbia win the mixed doubles 6-1, 3-6, 7-6.

"I have a superman partner and I want to thank him for giving such an effort," Jankovic told reporters.

"The injury is actually worse today, I think it's really inflamed. I am having a really hard time on the court and I really shouldn't be here but I will try as hard as I can."

Jankovic sported heavy strapping to her right thigh but looked a little more agile against Dulko than she had on Wednesday.

The Serb won the first set 12-10 on a tiebreak before quitting after being broken in the second game of the second set.

In the same group, Tatiana Golovin [Images] crushed Hsieh Su-wei 6-1, 6-1 before Arnaud Clement beat Lu Yen-hsun 7-6, 6-4 as France [Images] defeated Chinese Taipei 3-0.

HOSTS BEATEN

Earlier, former world number one Williams put the second-seeded Americans one up on Australia with a 6-2, 7-6 win over Alicia Molik [Images] before Mardy Fish [Images] overcame Peter Luczak 7-6, 7-6.

Williams and Fish then outclassed Molik and Luczak 6-2, 6-3 in the mixed doubles.

"I served really well today," said Williams. "Alicia has one of the best serves in women's tennis but I think I returned well and everything is coming together well."

In the other Group B match, Czech Republic defeated India 2-1.

Lucie Safarova held off Sania Mirza [Images] to put the Czechs ahead with a 6-2, 4-6, 6-3 victory before boyfriend Tomas Berdych triumphed 6-4, 6-0 against Rohan Bopanna.

Mirza and Bopanna took their Hopman Cup mixed doubles record to six wins out of six with a 6-3, 6-2 victory.

"It's a shame we didn't get to the final but at least we kept our unbeaten record," Mirza said.