Martin Kaymer tied the course record with an opening round of 63 to hold a two-shot lead at the Players Championship at TPC Sawgrass.
The German has gone more than two years since his last tournament triumph, but raised hopes of ending his barren run with a flawless nine-under round that saw him come home in 29 shots.
Lewis Hamilton was comfortably fastest in first practice for the Spanish Grand Prix on Friday morning ahead of Jenson Button and Daniel Ricciardo.
The Mercedes driver will be looking for his fourth straight win this weekend, in a bid to close the gap on team-mate Nico Rosberg who still holds the lead of the Drivers' Championship.
Andy Murray admits he needs to find some consistency in his game following a disappointing third-round exit at the Madrid Open on Thursday.
The Wimbledon champion was dumped out in the Spanish capital by Colombian Santiago Giraldo 6-3 6-2 - just a day after recording an impressive battling victory against Nicolas Almagro.
Alastair Cook insists he is still the best man to captain England despite considering his position after the woeful winter tour of Australia.
Speaking ahead of his side's first match of the summer season - a one-day international against Scotland on Friday - Cook admitted he sought the guidance of his teammates after doubting his ability as skipper.