Here are the key stats from the second round at Baltusrol:
• Walker and Streb tied the lowest 36-hole total score in PGA Championship history at 131. They became the eighth member of the club and first since Jason Dufner in 2013.
• Walker has three career top-10s in majors (all came in 2014 season) and his previous best 36-hole position in major was T-7 at 2014.
• Streb shot 7-under 63 on Friday, making him the 28th different man and third this year to card 63 in a major, the lowest score ever in any round of a major championship.
• Streb, who entered this week with six straight rounds over par in majors and missed the cut in each of previous three major starts, has only one bogey through two rounds. His last top-10 on the PGA Tour came at this tournament last year at Whistling Straits,
• Day fired his 18th major round in the 60s since beginning of 2014 season (tied with Stenson for most such rounds in that span) and is seeking his eighth win in his last 23 worldwide starts. A win would make him the only player besides Tiger Woods to win back-to-back PGA titles in the stroke-play era.
• Grillo (66-67) carded his two lowest career major rounds so far at the PGA and is vying to become just the fourth international player to win a major before turning 24 in the last 100 years (Rory McIlroy, Seve Ballesteros and Gary Player)
• Stenson (67-67) is a combined 30 under in his last eight major rounds. A win would make him only the fourth player 40-and-over to win multiple majors in one season (Mark O’Meara, Jack Nicklaus and Ben Hogan).
• Martin Kaymer's (66-69) only lower major 36-hole total score was at the 2014 U.S. Open, which he went on to win. Kaymer hasn't won worldwide in 58 starts since.
• Jordan Spieth sits six shots off the pace after a second-round 67, and with a victory would become the youngest three-time major winner since Gene Sarazen (1923) to capture three legs of the career Grand Slam.
• Dustin Johnson's missed cut snaps a streak of 25 straight made cuts on the PGA Tour. It was the longest active streak entering the week.
• Phil Mickelson managed to salvage an even-par 70 to make the cut. Mickelson, who missed the cut at the Masters and the U.S. Open has never missed cut in three majors in same season.
• Rory McIlroy, who missed eight putts inside 10 feet through two rounds, missed the cut in multiple majors for just the second time in his career (U.S. Open).
Note: Golf Channel’s editorial research unit contributed to this report.