Rafael Nadal of Spain reacts after his semi-final match against Gael Monfils of France during the ATP Qatar Open tennis tournament in Doha January 6, 2012. [China Daily]

Frenchman Gael Monfil supset top seeded Rafael Nadal, while defending champion Roger Federer pulled out of the Qatar Open for back injury on Friday.

Monfils will face third-seeded Jo-Wilfried Tsongain in an all- French finale here on Saturday. Doha serves as a tune-up for the first Grand Slam event of the year, the Australian Open, which will commence January 16 in Melbourne.

The former world No. 1 Nadal succumbed to a fourth-seeded Monfils 6-3, 6-4 on the hardcourt.

Monfils ended a five-match losing streak versus the 10-time major champion Nadal. After dropping the opening set on Friday, Nadal appeared to be back in the match against Monfils as he held a 4-1 lead in the stanza.

But the Frenchman shocked onlookers by taking five straight games to pull off the upset in 1 hour, 35 minutes. Monfils won 16- of-21 points to go from 1-4 down to 5-4 up.

Nadal is the reigning French Open champion, was last year's Wimbledon and US Open runner-up, and was a Doha finalist two years ago.

Monfils was the Doha runner-up back in 2006. The powerful Nadal and Monfils met for a 10th time, as Nadal still comfortably leads the lifetime series, 8-2.

The Frenchman, however, was a quarterfinal victor here in Doha two years ago. The 25-year-old Monfils will now appear in his 16th career final (4-11), seeking only a fifth title.

He was 1-1 in a pair of finals last year, including a big victory in Stockholm. Tsonga received a walkover into the final when the second-seeded former No. 1 Federer exited the draw on Day 5 with back spasms.

Federer said he expects to be ready for the Aussie Open. "For Australia, I'm optimistic, just because it's not very good but it isn't crazy bad," Federer said.

"I have had bad backs in the past. This is definitely not very good; otherwise I would be playing. But I feel without play and the right treatment, I will get through it in the next few days."

This marks only the second time that the 30-year-old Federer has withdrawn during an event because of injury.

The 16-time major champion Federer is a three-time Doha titlist, including a victory over Russian Nikolay Davydenkoin last year's finale.

The 26-year-old Tsonga will appear in his 13th career ATP World Tour final, seeking an eighth championship. He went 2-4 in his 2011 title tilts.

Tsonga and Monfils will meet for a fourth time, with Tsonga leading their all-time series 2-1, all on hardcourts.

The winner of this 1.24 million dollar tournament will claim 175,380 dollars.