Rory McIlroy started the week five shots behind Justin Thomas because of the unique scoring system on the Tour ChampionshipTour Championship – round two leaderboard (US unless otherwise stated) -13: B Koepka; -12: R McIlroy (NI), J Thomas; -11: X Schauffele; -9: P Casey (Eng); -7: P Cantlay; Selected others: -6: P Reed; -5: A Scott (Aus); -4: J Rahm (Spa); -2: T Fleetwood (Eng); Level: J Rose (Eng)

Rory McIlroy from Northern Ireland continues a shot from the lead after a three-under 67 in the second round of the season-ending Tour Tour Championship in Atlanta.

The 30-year-old is second for 12th with the American Justin Thomas, with US PGA champion Brooks Koepka winner in the 13th position.

Thomas, who started the tournament five shots for McIlroy because of a ranking-based system, carded a 68.

England Casey England is four shots in the lead on nine under after a 67.

McIlroy, who shot back-to-back birdies on his last two holes to take part of the second place, said he had "jumbled up well" but admitted that fortune had a role played.

"I was lucky at 18," he told Sky Sports. "I just drove my luck all the way down that hole.

" Most of the day three or four are behind those guys and then catch Justin Thomas and are just a Brooks back, it was nice to finish the way i did it. "

The seasonal tournament uses an adjusted sliding scale to determine the winner of the first prize of $ 15 million (£ 12.3 million) FedExCup, a system that McIlroy asked questions about.

It meant that Thomas started the week at 10 under and Koepka began at seven under, with McIlroy starting at under 5.

Koepka, who also carded a 67, mixed four birdies – including a two-putt birdie on par-five 18 – with a bogey.

But a weather delay interrupted his momentum and it was only at the last hole he could get ahead.

McIlroy benefited better from the 90-delay minutes by firing his first bird on the 12th before completing his round with a 15 foot rdie putt on the 17th and a closing birdie on the 18th.