The United States won a second straight Hopman Cup tie by edging winless France 2-1 on Tuesday.
France should have beaten the Americans after Jo-Wilfried Tsonga won the opening match by overwhelming John Isner 6-3, 6-2 in 55 minutes.
Venus Williams recovered from trailing by a set and 4-1 to defeat Mathilde Johansson 3-6, 7-5, 6-4 to level the tie, then the Americans won the mixed doubles 6-7 (5), 6-2 10-8 by snatching six of the last seven points in the match tiebreaker.
Williams appeared to be heading for defeat in her singles as a grim countenance and listless performance suggested she might be injured or suffering from her long-standing health problems.
She struggled against the adventurous Johansson, and even after earning the only break of the final set to lead 4-3 she faced two break points in the following game before holding for 5-3.
But, typically, she refused to explain what was behind her obvious discomfort.
"I'm OK thank you, I'm OK," she said. "She hits the ball hard and low and I'm tall so it was hard to get down that low all the time. I have to give her a lot of credit for a tough match."
Tsonga gave up just seven points on serve and committed only four unforced errors against 21 from Isner to claim a comfortable victory.
"It's never easy against John usually, so I'm really happy with the way I played today," said Tsonga, who had lost three of his previous four matches against the American. "It's a really good start for 2013 and I hope I will have some more like this.
"I was a bit quicker on court than before so I think it's a good sign for the rest of the competition and for Melbourne."
The Australian Open begins in Melbourne on Jan. 14.
Isner wore strapping on his right knee because of "a little tendinitis." He said he was not concerned at losing both of his singles so far at the Hopman Cup.
"Normally it takes me a while to get going," he said. "I'm not worried about it though. I remember three years ago when I first played this event I didn't play so well here but I won the next tournament.
"It certainly wasn't my best. I was missing shots I would have liked to have made, (but) I'm not freaking out about it."
On Wednesday, Italy plays Germany and Australia faces Serbia.