|Second round leaderboard|
|-9 S Lowry (Ire); -8 T Mullinax (US); -7 D Johnson (US), E Grillo (Arg); -6 CT Pan (Tpe), R Sabbatini (Svk)|
|Selected others: -5 I Poulter (Eng), G McDowell (NI); -4 T Fleetwood (Eng), M Kuchar (US); -3 J Spieth (US); -2 E Pepperell (Eng), S Power (Ire); -1 L Donald (Eng), X Schauffele (US), E Els (SA); Level M Fitzpatrick (Eng); +1 B DeChambeau (US); +2 D Willett (Eng); +3 R Knox (Sco), M Laird (Sco)|
Ireland's Shane Lowry led by one shot at the RBC Heritage when darkness suspended play with two holes of his second round remaining.
Storms had earlier delayed play in South Carolina, where Lowry, 32, had held a one-stroke lead after round one.
On Friday he improved to nine under par to stay clear of Trey Mullinax, who carded a three-under 68 in round two.
World number one Dustin Johnson and Emiliano Grillo are both seven under after shooting four-under-par 67s.
Taiwan's Cheng-tsung Pan is just a shot further back after climbing the leaderboard with a six-under 65, while Northern Ireland's Graeme McDowell and England's Ian Poulter are among a large group on five under par.
Lowry is among 56 players, which also includes McDowell, Donald and Tommy Fleetwood, who must complete their second round at Hilton Head on Saturday before starting the third later in the day.