The four-time major champion took full advantage of the par-5s all day with birdies at the 2nd, a stunning eagle at the 8th and further birdies at the 13th and 15th.
It all added up to a brilliant round of 67 as Koepka looks on from the top of the board at 12-under par thru 36 holes.
Koepka was asked after his second round whether or not his decision to move to LIV Golf last season would have been more challenging had he been as fit and healthy as he is at Augusta National this week.
Brooks nodded and said:
Koepka has been fighting multiple injuries in recent years but the American has made it clear he now has no injury concerns at all.
That was further evident last week when Koepka became the first player on LIV Golf to win twice on the circuit with victory in Orlando.
Koepka was reportedly offered $125m to move to LIV Golf in 2022.
As it stands at the time of publication, Koepka leads The Masters by four strokes over amateur Sam Bennett, who is producing some magical golf out there.
Bennett carded a consecutive round of 68 to reach 8-under par and give himself every chance of becoming the first amateur golfer to win The Masters.
The lead could be closed further with joint overnight-leaders Rahm and Hovland in the early stages of their second round.
Koepka is bidding to win The Masters for the first time in his career.
Should he go on to win, Koepka will just need to land The Open in order to complete the career grand slam.
Jason Day had been going in search of Koepka for much of the round, but the Australian dropped four shots on the last four holes to fall from 9-under back to 5-under.
Elsewhere, defending champion and World No.1 Scottie Scheffler, who played with Bennett, had a day to forget with a dismal round of 75.
Scheffler has made the cut but he looks on from 11 shots off the pace at 1-under par.
McIlroy's wait for the career grand slam this week is over as he missed the cut on 5-over par.
The World No.2 opened with a lacklustre 72 and then followed it up with five bogeys over the first 11 holes of his second round to play his way out of contention.
McIlroy birdied the 13th and 15th but he then handed those shots back with bogeys at 16 and 18 en route to a shocking round of 77.
Tiger Woods is still out on the course doing his best to make the halfway cut.
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