Danny Willett trails Rory McIlroy as Matt Fitzpatrick shows his mettle after mid-round stumble in Dubai

Willett added a two-under-par 70 to his opening 68 while McIlroy - who has a lead of just 1,613 points over the Yorkshireman at the top of the R2D rankings - carded a second consecutive 68.

The Nedbank Challenge and Euro Masters champion will need to better the four-time major champion over the weekend's final two rounds if he is to lift the near $2m bonuses that will go to the season's top player.

Willett is tied 13th, a shot back of fellow Sheffielder Matt Fitzpatrick (68 69).

British Masters champion Fitzpatrick was two under for his round after consecutive birdies at holes two and three.

He then tottered back into the pack with three bogeys in a row from the seventh, but demonstrated the resilience that has stood him in good stead in a stellar debut season on tour by birdieing four of the last six holes.

He lies tied seventh behind leader Andy Sullivan, the only three-time winner on the European Tour this season who is threatening to make it four following back-to-back 66s for a one-shot halfway lead.

McIlroy felt he was stuck "somewhere between third and fourth gear" after a second round that leaves him, four shots behind Sullivan, but crucially ahead of Race to Dubai rivals Justin Rose and Willett by one and two shots respectively.

Sullivan leads by one from Argentina's Emiliano Grillo, much to the delight of "Team Sulli", his 30-strong personal fan club from Nuneaton who have travelled to Dubai for the £5.2m season finale.

Already the only player to win three times on the European Tour this season, Sullivan could take his official earnings for the year to almost £2m with the first prize of £875,000 and his share of the £4m bonus pool shared between the top 15 players on the Race to Dubai.

Not bad for a man who spent two years stacking shelves in Asda to fund his golf.

"If you ask them they'll probably say I was only there for about six months because I was asleep in the changing room half the time," joked Sullivan.

"I had to go in at five in the morning and finish at 10 so I could play golf, so a few times I turned up with a bit of a hangover, seeing as I had to work on Thursday, Friday, Saturday and Sunday.

"Working in Asda and having a little girl (Ruby was born in 2013) put a massive perspective on life. This is my dream and I've always wanted to do it. I couldn't imagine doing anything else. So if I can't enjoy it, I'd best go and do something else. Go back to stacking shelves at Asda I think.

"It's absolutely awesome to be leading after halfway in such a massive event, it's incredible. I'm just happy I'm doing it in front of my fans, to keep them happy for the weekend anyway.

"They have followed me about six or seven times this year and every time they have been there, I've done pretty well. I think I am going to have to start paying for them to come out every week now.

"You feel like everyone's behind you and you feel like you're really using that as momentum. I felt a bit static through holes eight, nine, 10 and 11 and holed a massive putt on 12, the crowd get wild and you feel like you're pushing on from there. I think it's massive to use that to my advantage."

Rose is more than 600,000 points further back than Willett behind McIlroy and needs to finish second or better to overtake his Ryder Cup team-mate. Even a victory on Sunday would not be enough for Rose if McIlroy was outright second.

"I'm treating it like a normal event because I'm just here to win and I know if I win, then everything else will take care of itself," McIlroy said. "I'm not quite performing at the highest levels I would like to.

"I'm hitting it well. I feel like my putting's getting better. I still missed a few chances but I scrambled well today. All facets of my game are pretty much there, it's just a matter of being a little more efficient, taking advantage of the par fives a bit better.

"I saw first hand how well Emiliano is playing but I just have to try and put another solid round in tomorrow and give myself a chance on Sunday."

Playing alongside McIlroy, Grillo carded eight birdies in a flawless 64, the lowest round of the week, to maintain the form which saw him win the Web.com Tour Championship and Frys.com Open in the space of a fortnight last month.

"It gives you a lot of confidence," said the 23-year-old, who almost hit McIlroy with a tee shot on his way to a first PGA Tour title in California. "We know there it's not easy. Anywhere it's not easy. I was lucky enough to get two wins in a row and that gets me twice the confidence.

"But here it's pretty much like a major. You've got the best players in the world and you've got to play really well to keep it up. It was my second time playing with Rory and I'm really thrilled. He's one of the nicest guys out here and that makes it easier, but it's nice playing good with him."

Rose correctly anticipated being five off the lead after adding a 66 to his opening 71 to finish seven under par, with former Masters champion Charl Schwartzel and Thongchai Jaidee alongside McIlroy on eight under and American Ryder Cup star Patrick Reed nine under.