Venus Williams shows her fighting spirit in victory over Barbora Zahlavova Strycova at Qatar Total Open

American through to quarter-finals in Doha

Venus Williams (GETTY IMAGES)

She may not be the force she once was, but Venus Williams’ fighting spirit is as strong as ever. The former Wimbledon champion, who last month reached her first Grand Slam quarter-final for five years, became the first player to reach the last eight of this week’s Qatar Total Open when she won a gruelling contest here against Barbora Zahlavova Strycova that lasted nearly three hours.

It was 1.30am on a chilly night when Zahlavova Strycova hit a foreland long on match point as Williams won their second-round contest 7-5, 3-6, 7-6 after two hours and 54 minutes. If the quality of the tennis dipped at times, there could be no doubting Williams’ determination.

Williams, who will turn 35 in June, had won the first set and had not appeared to be in too much danger in the second until Zahlavova Strycova broke serve to lead 4-3 after defying her opponent with some heroic defensive work. The 28-year-old Czech, who is at a career-high No 22 in the world rankings, broke again two games later to take the set.

However, it was Williams who set the pace in the decider. Zahlavova Strycova dropped serve in the third game and had to break to stay in the match when Williams served at 5-4. The Czech went 6-5 up and had a match point when Williams served at 30-40, but the match went to a deciding tie-break. At 6-5 to Williams, Zahlavova Strycova finally succumbed with a missed forehand.

For a long time after Williams’ diagnosis in 2011 with an incurable auto-immune disease - Sjogren’s Syndrome causes joint paint and fatigue – the five-times Wimbledon champion struggled to recover her former glories. In the space of three years she won just one minor title. The American even dropped out of the world’s top 100, though she fought hard – and successfully – to earn a place at the 2012 Olympics.

However, Williams enjoyed her biggest win for four years when she won the title in Dubai 12 months ago and has since continued to rebuild her world ranking. She is currently at No 17, having enjoyed a fine start to the year.

After beginning the season by winning the title in Auckland, Williams then enjoyed her best run at a Grand Slam tournament since 2010 when she reached the quarter-finals of the Australian Open by knocking out the then world No 6, Agnieszka Radwanska. She eventually lost to her fellow American, Madison Keys.

Williams is playing in her fourth tournament of the year this week. “I've been going non-stop this year,” she said. “I've played so much and it's only February. So far I'm happy.”

The former world No 1 has also found time to play in the Fed Cup, helping the United States to a convincing victory over Argentina. Players have to represent their country in the Fed Cup to be eligible for the Olympics and next year’s Games in Rio are a major target for Williams.

“That's why I was at Fed Cup,” Williams admitted. “I love playing Fed Cup, but it's hard to play with the schedule. It doesn't give you a break at all. So it's definitely important. I hope I can get there and play well for my country.”