Rory McIlroy will go into the weekend four shots back at the Travelers Championship after a second round 68 at TPC River Highlands in Connecticut.
The World No.1 lies at nine-under-par for the tournament and is four shots back of halfway leader Phil Mickelson, who played with McIlroy the first two days and set the pace at 13-under-par.
However, Friday was another day where coronavirus reared its head on the PGA Tour as Denny McCarthy became the third player on tour to test positive for the virus.
Despite testing negative for Covid-19 twice, McCarthy's playing partner Bud Cauley also withdrew from the event as a precaution, with the likes of Graeme McDowell, Webb Simpson and Brooks and Chase Koepka all pulling out of the event prior to its start.
McIlroy was among those to claim that cancelling the tournament due to the positive tests would be "silly" and he put those concerns behind him to continue his charge on Friday.
The 31-year-old battled back from bogeys at both par-threes on the front nine to card three birdies prior to the turn, then parred his way in after another birdie on the 11th for a two-under-par round.
But he was overshadowed by playing partner Mickelson who, despite having 19 years on McIlroy and the third member of their group, Bryson DeChambeau, went lowest of them all.
The five-time Major champion showed his full range of accurate wedge and iron play in recording five birdies on his inward nine on the way to a seven-under-par 63 that his him leading by one.
Mickelson's closest rivals are the relatively unknown Will Gordon, who is only in the field as a sponsor's invite this week, and Canada's Mackenzie Hughes who flirted with a 59 on Thursday.
Xander Schauffele, Brendan Todd and Marc Leishman are also alongside McIlroy at nine-under in a four-way tie for fourth, with defending Open champion Shane Lowry making the weekend at five-under.