To reckon from his testy deportment under Dan Rather's grilling, Vice President George Bush wasn't kidding when he said he didn't want his whole career judged "by a rehash on Iran."

Fine. How about judging it by a rehash of the one day -- Saturday, July 13, 1985 -- when he was, to all intents and purposes, acting president of the United States?

It's a day already immortalized by cartoonist Garry Trudeau (Interviewer: "How will history judge the Bush hours?" Vice president: "I think history will be very high on them, Roland. Remember, not a single country fell to the communists during my watch"). But "Doonesbury's" creator, it seems, didn't know the half of it.

According to yesterday's Jack Anderson column, Bush's account of his commander-in-chieftaincy omits any mention of an historic tennis game on the grounds of his residence -- and thus any mention of a vice presidential tumble that left the nation, however fleetingly, with both its leaders down for the count.

Dale van Atta, who shares the Anderson column's byline, wrote that while President Reagan was anesthetized for removal of a tumor in his lower intestine, Vice President Bush, too, was "out of commission" after a spill on the tennis court. Van Atta's confidential sources, "including high-level White House officials," declared that Bush was "unconscious" for an unspecified time after the mishap.

Responding to inquiries yesterday, Bush's aides echoed the denials they had given van Atta, whose column was dispatched to newspapers long before Bush's confrontation with Dan Rather Monday evening.

Bush campaign communications director Pete Teeley admitted that the vice president had fallen. "He did bang his head on the court," Teeley said. "It was a very hot day, hot as hell ... He sat down and had some lemonade and relaxed." Teeley was not in Bush's employ at the time, nor, he says, was he present at the tennis court.

Did the vice president black out after his fall? Not according to a witness who was at his side during the full 474 minutes of the Bush administrationette.

By this account, after returning hurriedly from his vacation home in Kennebunkport, Maine, late Saturday morning -- limited presidential powers were transferred to Bush in midflight -- Bush drove to his official residence and rounded up three players, as yet unidentified, for a tennis game. It was, this source says, echoing Teeley, "hot as hell."

During the second set, with Bush playing aggressively at the net, a lob from the far court arced high over the vice president's head. Stepping back to position himself for a return, Bush stumbled and fell over backwards -- "whooompf" is how the witness recalls the sound of the impact -- on the hard surface of the court.

"We all leaned forward," he continues -- the vice president's doctor, his Secret Service detail, his fellow players -- and "the same thing flashed through all our minds."

At that moment, on Cape Cod, the man next in line for the presidency, then-House Speaker Tip O'Neill, was most likely well into the second nine holes of his usual Saturday afternoon golf game at the Eastward Ho! Country Club -- and may or may not have felt the mantle of higher office brush across his shoulders.

Back on the tennis court, relief was immediate. "The vice president rolled over and got up and walked off the court," the witness says. Unaided? "Unaided." The doctor asked him if he was all right, and Bush said he was, but allowed as how "I think I'll just call it a day."

(At the time of the fall, the witness notes, Bush and his partner were winning the set.)

The vice president then traveled by motorcade the several hundred yards to his house, where he and his guests sat on the porch and "had a lemonade" -- the same refreshment mentioned by Teeley. "There was no 'sleeping it off,' " as the Anderson-van Atta column alleged, according to the witness. "He had work to do and he did it."

At 7:22 that evening, as the anesthetic wore off, President Reagan reassumed his official powers, marking an end to Bush's topsy-turvy stewardship of the nation.