LIEZEL HUBER is very protective of Wimbledon mixed doubles partner Jamie Murray.

"I know Jamie, and I take offence if people say he's had a tough year," she says.

Since Huber is a rather feisty woman, who refused to give up yesterday despite nearly collapsing from heat exhaustion, it would take a brave man to argue with her.

But here goes: the older of the Murray brothers has had an appalling season playing doubles.

From a career-high 27 in the men's doubles rankings in February, Murray has plummeted to 75 and may drop further after losing in the first round here last week.

Since splitting with Eric Butorac, with whom he won three titles in 2007, Murray has struggled in the men's game. This year he has gone through eight partners, and in 18 tournaments has got beyond the quarter-finals just once.

The one constant on court, at least for the past 18 months, has been Huber, the 32-year-old born in South Africa but now based on her own tennis 'ranch' in Texas.

The two teamed up by accident after Jelena Jankovic decided to concentrate on singles tennis despite winning the Wimbledon mixed title with Murray in 2007. The Briton's search for a replacement originally resulted in an approach to Huber's women's doubles partner Carla Black.

But since Black already had a mixed doubles partner, Huber stepped in. She and Murray clicked immediately, reaching the semi-finals at the US Open. The following year they reached the final in New York, losing to Black and Leander Paes. They also reached the semi-finals at Wimbledon and the quarter-finals in the French Open.

Now Murray and Huber have the chance of taking the title at SW19 this year, offering the intriguing possibility of both Murray brothers playing in finals on Sunday.

Following a three-set victory over American sixth seeds Mike Bryan and Bethanie Mattek-Sands yesterday, they learned that scheduled quarterfinal opponents Lukas Dlouhy and Iveta Benesova, from the Czech Republic, had pulled out through injury.

They could now face the other Bryan brother, Bob, and Samantha Stosur, in tomorrow's semi-finals. That pairing knocked them out at the same stage 12 months ago.

Murray knows what is at stake. "My year's been really disappointing," he conceded. "If we do win, it would put a shine on it. I haven't been playing so well the last couple of months."

Andy Murray added: "Jamie's struggled this year so it's important for him to have a good run here. But he looks confident on the court, from what I've seen of the last few matches, which is good.

"He's now a couple of matches away from winning Wimbledon again. Regardless of the year he's had, I'm sure he'd be very happy if he won another Wimbledon title."

Jamie acknowledged the importance of Huber in the partnership. He said: "Liezel is fantastic. She is not the No1 ranked women's doubles player for nothing.

"She has fantastic motivation and is brilliant on the court. She keeps saying we have a grand slam win in us after narrowly missing out in the US Open."