Dustin Johnson leads by one stroke after the opening round of the 2015 Open Championship at St. Andrews. Here are some key stats provided by Golf Channel's editorial research unit.

• Dustin Johnson: 7-under 65 ties lowest career round in any major

• Second straight major to open with 65 (U.S. Open, finished T-2)

• Third bogey-free round in major championship career

• Played first five holes of round in 4 under

• Finished runner-up at U.S. Open; leads after first round at St. Andrews

• Last to do that was Tiger Woods in 2005 (won Open Championship)

• Fifth straight opening round under par in a major

• Fifth straight round of par or better in Open Championship

• Jordan Spieth: 5-under 67; opened Masters and U.S. Open with 64 and 68

• Combined 28 under par in major championships this year

• Has birdied 32.7 percent of holes in majors this year (53/162)

• Best first round score in Open by player to win Masters and U.S. that year

• Birdied five of first seven holes in round (even par rest of round)

• Combined 25 under over last four rounds of competition

• Eight of nine rounds this year in majors have been under par

• Zach Johnson: 6-under 66; third time in four years to begin The Open with 66 or lower

• Fourth 66 or lower in last 13 Open Championship rounds played

• Ninth straight round of par or better overall in competition

• Three best opening rounds in majors have all come in Open Championship

• Jason Day: 6-under 66; lowest career first round score in any major

• First career round in the 60s in The Open Championship

• Fourth straight major to open with round in the 60s

• Fifth career bogey-free round in a major (first in The Open)

• Five top-4 finishes in majors (0 wins); all since beginning of 2011

• Phil Mickelson: 2-under 70; Sixth time to begin Open Championship with round under par

• Phil Mickelson: Last instance – 2013 (shot 69, went on to win)

• Tiger Woods: 4-over 76; worst first round score of Open Championship career

• Worst score in an Open at St. Andrews as a professional

• Only birdie came on 14th hole

• Combined 21 over in last four rounds of major championship golf

• 27 bogeys or worse over last four rounds in majors (6.8 per round)

• Opening round scoring average of 73.88 this year (one round under par)