Ryder Cup hero Martin Kaymer has a battle on his hands to claim a £1million payday in the Players Championship at Sawgrass.
Kaymer held a two-shot advantage overnight thanks his course record-equalling 63 on Thursday and was five clear of the field when he added a 69 on Friday for a halfway total of 132, 12 under par.
But that lead was cut to a single shot by rising star Jordan Spieth, the American the only player in the field without a single bogey in the first 36 holes.
The 20-year-old added a flawless 66 to his opening 67 as he looks to win golf's so-called 'fifth major' just a month after almost becoming the youngest Masters champion in history.
Spieth only turned professional in December 2012 and was a 19-year-old special temporary member on the PGA Tour when he won the John Deere Classic last July, the youngest winner on Tour since 1931. But he held a two-shot lead after seven holes of the final round at Augusta before finishing joint second behind Bubba Watson.
Kaymer had birdied his last four holes in the opening round and was soon making further progress when he holed from 25 feet on the third, but dropped his first shot of the week on the seventh after driving into a fairway bunker.
A birdie on the ninth took the 29-year-old out in 35 and three more birdies and one bogey on the back nine meant Kaymer - who secured the point to ensure Europe retained the Ryder Cup in 2012 - set a testing target for the later starters.
Kaymer, who won the US PGA Championship in August 2010 and became world number one the following February for eight weeks, said: "It was very difficult today.
"It was a little tougher especially when you shoot such a low score, your expectations are very high and you need to find a way to lower those expectations and see it as a new day, so 69 was a very good score today. The pins were in some corners and it was more windy, so I am very pleased.
"I didn't hit as many fairways as yesterday, but I managed my way quite nicely around the golf course, had a couple of nice up and downs and two longer putts went in. I think I kept it really well together and kept myself in the tournament.
"It's a great start, but we are only halfway."
Kaymer's last win in a full-field event came in 2011 but the German has been moving in the right direction this season and added: "I've had a lot of good finishes.
"I was very happy the way I played golf the last four or five weeks, so the next step is just putting yourself in contention, hopefully win. If not, it's okay, but as long as you put yourself in contention for the next few weeks, especially now we're coming up to the US Open and British Open.
"It would be nice to gain even more confidence and if you sneak in a win here and there it would be nice. If not, it's still good golf and good performances."
Lee Westwood, Justin Rose and Sergio Garcia were all six shots off the lead after adding rounds of 71 to their opening 67s, with England's Brian Davis a shot behind after a 67.
Adam Scott endured a long wait before discovering his latest bid to become world number one remained alive, the Australian rebounding from his opening 77 - which featured double bogeys on the 17th and 18th - to return a 67 with three birdies in his last four holes.
Scott, who could have overtaken the absent defending champion Tiger Woods by simply staying at home, needed at least a top-16 finish and eventually discovered his level-par total made the weekend right on the mark.
"I don't think I played that much better than yesterday to be honest," said Scott, who revealed he married his long-term girlfriend Marie Kojzar in a small ceremony at his home in the Bahamas last month. "Hopefully it will be good enough to play the next few days. If not it will be disappointing."
Rory McIlroy also made the cut on level par, the 25-year-old recovering from a front nine of 42 with birdies on the 12th, 13th, 16th and 18th in his 74.
Henrik Stenson, Bubba Watson and Matt Kuchar were also able to overhaul Woods depending on their results, with Stenson needing a top-six finish, Watson to finish alone in second and Kuchar requiring a victory.
European number one Stenson and two-time Masters champion Watson were three under, with Kuchar two under after a second consecutive 71.