Considered the toughest test of golf this side of the Atlantic and perhaps worldwide, the U.S. Open routinely has made some of the game’s most skilled players look foolish. In 2006 and ’07, for instance, 5 over par was the winning score, and last year, no player shot below par for the tournament.

So at this year’s U.S. Open, where sub-par scores have gone viral, more than a few players marveled at how benign the conditions were at Congressional Country Club, which is renown for fast greens and rough as punitive as just about any course in the land.

“I’ve been a little disappointed with the golf course the last couple of days,” said Graeme McDowell, who won last year’s U.S. Open at Pebble Beach with an even-par 284. “It wasn’t as firm and fast as I would like to have seen it. . . . So it’s not a true U.S. Open test out there, to be honest.”

McDowell shot 2-under 69, and that wasn’t even close to the low round of the day. Lee Westwood and Jason Day each shot 65 in the afternoon after Webb Simpson, playing in the third group, led off a third round replete with low scores by firing a 5-under 66.

Those single-round scores eclipsed Ernie Els’s cumulative winning result the last time the U.S. Open came to Congressional in 1997. That year, Els shot 4 under, one better than Colin Montgomerie and two better than Tom Lehman. They were the only players below par for the tournament.

This year, 26 players shot sub-par scores Saturday, breaking the third-round record of 24 set at Medinah in 1990. The record for most sub-par 72-hole totals — 28, also at Medinah in 1990 — is in jeopardy, as well. Twenty players enter the final round in red numbers, and another six are at even-par for the tournament.

“It’s there for the taking right now,” said Harrison Frazar, who shot 3 under in the third round.

Nothing figures to change much during the final round either thanks to a forecast that calls for more rain overnight. The course already received a heavy drenching late Friday afternoon and light rain during the first two rounds, allowing players, most notably leader Rory McIlroy, to attack flags in some cases regardless of pin placement.

McIlroy enters the final round 14 under par and on pace to set the tournament scoring record that Tiger Woods established in 2000 when he was 12 under at Pebble Beach.

“I don’t think we’re going to try to trick Mother Nature,” said Tom O’Toole, USGA championship committee chairman. “This is what we got in 2011. You come to the U.S. Open in the District of Columbia or in Maryland in June, that’s the dice you roll. That’s what we’ve got. We ended up with a soft golf course.”