American Ryan Moore completed a six-under-par 65 as darkness fell in Illinois to carry a one-shot lead into the final round of the weather-hit John Deere Classic.

On a long day at soggy TPC Deere Run, where the second round was completed early on Saturday, Moore and his playing partners hustled through their last holes in fading light to avoid an early wake-up call to finish the third round on Sunday. 

It was the second 65 shot by Moore on Saturday as he never got on the course on Friday because of the rain delays. 

In the third round, Moore held off spirited charges by compatriots Ben Martin and Morgan Hoffmann, who both recorded nine-under-par 62s to reach 17-under 196 for a share of second place, three shots better than Johnson Wagner.

"It is dark," said Hoffmann, who finished earlier than Moore. "It is really dark, and the last few greens are getting really soft and bumpy, too, so it was hard to read."

Aided by the glow of light coming off the giant electronic scoreboards alongside the 18th green, Moore had a chance to gain one more stroke but lipped out his birdie putt at the last. 

Low scores were readily available on the softened course where players were allowed preferred lies after 3.5 inches (8.9 cm) of rain drenched the layout over a 24-hour period. 

Martin took advantage by starting the third round with five straight birdies and then closed with birdies on four of his last five holes. He rolled in a 44-footer from short of the green for a final birdie at the last. 

"It was one of those days where all the putts were going in," said Martin. 

Hoffmann, seeking his first PGA Tour win, briefly tied Moore for the lead late in the round as he rocketed up the leaderboard with six birdies in a row from the 11th before Moore birdied the 16th to regain the sole lead.

"It was great. Really exciting to make six birdies in a row," said Hoffmann. "Definitely fun."