Andy Flower, England team director, has kept up the pressure on Samit Patel to reach acceptable fitness levels if he is to achieve his ambition of a Test debut for England against Sri Lanka in Galle later this month.

Flower regards Patel as a genuine contender to bat at No. 6 and strengthen England's slow-bowling ranks as they seek to improve on their disastrous 3-0 whitewash against Pakistan in the UAE. But as the bulk of England's squad prepared to leave Heathrow, he issued a subtle reminder of the fitness standards required to survive the sapping conditions of Sri Lanka at one of the most humid times of the year.

"I think he's still got significant work to do on the fitness front but he's inching in the right direction," Flower said. "The heat and humidity will be a significant factor for the bowling side certainly and then on concentration levels because fatigue affects everyone. Fitness levels and how we react will be very important."

The makeup of England's bowling attack will influence whether Patel will make his Test debut in Sri Lanka. Flower and England captain Andrew Strauss will have to decide whether to continue with two specialist spinners, a policy that served them well against Pakistan in the UAE, revert back to three quick bowlers, or play five bowlers - something England have been reluctant to do but an option Flower has not ruled out.

"Everyone in this squad is a serious challenger for a Test place," Flower said as England prepared to fly out to Sri Lanka ahead of the first of two three-day warm-up matches on March 15. "Patel provides the option of flexibility for us. If we played three quicks and Graeme Swann, then he could bat at six and give you that angle to bowl into the rough if we needed to. That is a possibility.

"If the conditions determine that two spinners should play, they can take up a lot of the slack on the workload front. It doesn't necessary mean you have to play five bowlers. We saw two and two work effectively in the UAE and I still think with two specialist spinners taking up a lot of the overs you can still take 20 wickets with four bowlers."

England, who could begin the Sri Lanka series below South Africa in the Test rankings, also have James Tredwell, the 30-year-old Kent offspinner, in their squad. A surprise selection, he is only likely to feature through injury to Swann. "James is an experienced cricketer who we know we can rely on," Flower said. "Both types of spin are important and we've covered both."

He sounded unconcerned that Tredwell has not played since the end of last season. "When you've played as long as Tredwell has, it won't take long to get him up to speed."

Tredwell is one of seven England players that have flown out early to Sri Lanka to acclimatise. Ian Bell, reserve wicketkeeper Steven Davies, Monty Panesar, Patel, Matt Prior and Andrew Strauss have also travelled early for two skill sessions a day and fitness training.

Strauss is looking to find form after a lean period in Test cricket: his last century came in Brisbane in November 2010. But Flower sees the improvements Strauss made towards the end of the Pakistan series as signs of returning form. "To survive and thrive you have to be adaptable and he showed some of that adaptability in that last Test," Flower said. "He's working at those skills and methods right now and he's got two three-day games to get some time in the middle. With his experience I expect him to do well."

Flower said that Strauss was not helped by an extended break between the end of the season and start of the Pakistan series but that a similar scenario was unlikely happen again and Strauss was keen to lead from the front once more. "He's a very experienced cricketer and you know that he's very level-headed in his response to both the highs and lows associated with playing for England. I know he will be working hard and smart to get his game in order."

Strauss will return to the England top order alongside Alastair Cook, who, along with Kevin Pietersen, found form in the 4-0 ODI series win against Pakistan. Their performances and the experience gained against Pakistan's barrage of spinners is cause for optimism for Flower. "The good thing about playing people like Seed Ajmal is that as you're exposed to them you should get better, that's how we grow, by putting ourselves in tougher situations that we'd normally come across.

"Playing in subcontinental conditions against good spinners will without doubt add to our batsman's growth. So I should expect our batsman to be better able to deal with Sri Lanka's spinners."

Alex Winter is an editorial assistant at ESPNcricinfo