Promising youngster Jordan Spieth moved into a share of the lead at the AT&T National before play was suspended for the day due to a band of storms moving through the area at Congressional.
Spieth, who does not turn 20 until July 27, carded a sublime 66 following his 69 yesterday to move onto seven under par overall, alongside overnight leader Roberto Castro.
The pair had a two shot lead before the action was suspended just before 3pm local time due to darkening skies and dangerous weather in the area.
Play was set to resume three hours later, but the inclement weather forced organisers to schedule the remainder of the second round for 7am tomorrow local time.
"You start feeling nerves when you know you're at the top of the leaderboard" - Jordan Spieth
US Walker Cup star Spieth looked as if he was going to race out in front on his own as he reached the turn in 31, but he parred all the way home to join Castro, who recorded three birdies and a bogey in his two under par round.
"Obviously you start feeling nerves when you know you're at the top of the leaderboard but I was able to to channel them nicely," Spieth said to the PGA Tour's official website.
"They didn't affect my ball-striking and I had a few putts that just barely missed on the back-nine and I'm looking for them to fall tomorrow."
If Spieth goes on to triumph in Maryland, he would - at 19 years, 11 months and three days old on Sunday - be the PGA Tour's fourth youngest winner since 1900.
The former University of Texas standout and Castro are two shots clear of DH Lee of South Korea and Andres Romero, who will be looking to make his mark tomorrow after seeing his round cut short after the 13th hole.
The Argentinean was on four under for his round and was on something of a role following back to back birdies before play was halted.
American pair Cameron Tringale and James Driscoll managed to complete their rounds and are on four under overall, with 2009 Open champion Stewart Cink one of seven players one shot further adrift.
Bill Haas and Nick Watney are also four shots off the lead, but can put themselves firmly into the mix at the halfway stage when they complete their second rounds tomorrow.