Serbia reached the Hopman Cup final on Thursday despite losing 2-1 to Belgium in their final round-robin series.
Serbia blanked both Kazakhstan and Australia this week and only needed to win one match against Belgium to advance.
Novak Djokovic took care of that, beating Ruben Bemelmans of Belgium 6-3, 6-2 after Justine Henin had defeated Ana Ivanovic 6-4, 6-3.
Henin and Bemelmans then won the mixed doubles 3-6, 6-4, 10-4 (Champions tiebreaker). Serbia will meet either Italy, France or the United States from Group B in Saturday's final.
"We were really eager to win it," said Djokovic, who is playing his first Hopman Cup since 2007, after leading Serbia to the Davis Cup title in December. "It was five years ago, the first time together, we were young and not experienced, and we did not have luck to go through the finals. This time we were winning quite comfortably, our matches, and really playing well. Both of us, we have a good chance to win the trophy."
Henin won her third straight match at the event and showed no sign of a lingering elbow injury. She raced out to a 4-1 lead in the second set before closing out the match.
"I thought today was probably one of the worst matches I played lately and I really got down on myself," Ivanovic said. "I have to be a little bit more aggressive than I was today. It's just getting through more matches and getting more confidence."
Also Thursday, Australia swept Kazakhstan 3-0, with Lleyton Hewitt and Alicia Molik teaming up to beat Andrey Golubev and Sesil Karatantcheva.
Hewitt produced his best performance of the week at the mixed team event in beating Golubev 6-3, 6-3.
"I played him at the French Open a couple of years ago and he's a great shot-maker, so it was important for me to go out there and weather the storm against him," Hewitt said. "But not get too far back either where he can feel like he's getting a lot of midcourt balls that he can dictate play and put me on the defensive. It was a bit of a balance for me."
Molik beat Karatantcheva 6-3, 6-2 before the Australian duo won the mixed doubles 8-7 (1) in a pro set.