Virginia running back Kevin Parks had somersaulted into the end zone, and the Cavaliers had just completed a nifty trick play for the two-point conversion, so Coach Mike London celebrated midway through the second quarter. He pumped his fists on the sideline and chest-bumped his players, who now had their largest lead against a Football Bowl Subdivision foe this season.

If only he knew then about the collapse that would follow.

A season that was already teetering on the edge of disaster took a turn for the worse Saturday as Virginia watched Duke leave Charlottesville with a 35-22 victory the Cavaliers once led 22-0. Virginia (2-5, 0-3 ACC) has lost four straight games, and any hopes of making a bowl game appear unlikely with a daunting schedule remaining.

“We have to learn how to win,” London said during a solemn postgame news conference. “We have to learn after coming off last week’s last-second loss [at Maryland] that one half is not good enough to win.”

Rarely does a football game against Duke qualify as anything meaningful, and the half-empty stands at Scott Stadium suggested many Virginia fans agreed with that sentiment. What transpired on the field, however, offered a clue into the desperate straits the Cavaliers now find themselves.

On an afternoon when Virginia gained 280 yards in the first half and scored on its opening possession of the game for the first time all year — thanks in part to a well-timed fake punt — it still managed to lose to Duke for the fifth time in six years. And the miscues that led to such a drastic turnaround — the Blue Devils scored 35 unanswered points — will be hard to move past.

“It got ugly fast, and we’re not proud of the product we put out there,” senior Luke Bowanko said.

The Blue Devils completed their comeback early in the fourth quarter when quarterback Anthony Boone faked a pitch on fourth and one and found tight end Braxton Deaver on a short completion. Deaver then ran through the entire Virginia defense for a 47-yard touchdown catch. A two-point conversion by wide receiver David Reeves gave Duke a 25-22 lead, but the entire sequence could have been avoided had safety Anthony Harris held on to what would have been an interception earlier in the drive.

Once the Blue Devils grabbed the lead, the Cavaliers miraculously converted a third and 18 when an errant pass by quarterback David Watford bounced off Duke’s Ross Cockerell and into the arms of Parks for a first down. But a 39-yard field goal by place kicker Alex Vozenilek, which would have tied the score with less than eight minutes remaining, was negated when offensive lineman Jay Whitmire committed a false start. Vozenilek then hooked a 44-yard attempt wide left.

After Virginia went up 22-0 with 5 minutes 49 seconds remaining in the second quarter, Duke outgained the Cavaliers 371-77. The Blue Devils converted all four of their fourth-down conversions after halftime, and they’ve now outscored Virginia 56-0 in the second half the past two years.

“Once again, we beat ourselves, offensively and defensively,” linebacker Henry Coley said.

Virginia’s offense was almost nonexistent in the second half. At one point, the Cavaliers had five straight drives in which they did not pick up a first down. Watford tied his career high with 263 passing yards, but he overthrew several receivers and missed others who were wide open.

With the Blue Devils stacking the box, Virginia mustered just seven rushing yards after halftime.

“You could tell when things started to go wrong for us. A lot of guys were hanging their head, and a lot of guys just didn’t think we were in it, and that really affects us,” Watford said. “When we face some adversity, we fall apart, and that’s what’s really killing. We have to, as an offense, just be able to fight through adverse situations.”

Still, what made the afternoon so frustrating was a first half Virginia can only hope to replicate the rest of the season. The Cavaliers scored touchdowns on three of their first five drives, and Duke earned just one first down during the entire first quarter.

Parks capped off the surge with a play that is destined to be on highlight reels the rest of the weekend.

With Virginia facing third and seven at the Duke 13-yard line, he nearly dropped a check-down pass from Watford before pinning it with one hand against his right leg. Parks (88 yards receiving, 50 yards rushing and three touchdowns) then completed a flip over two Duke defenders and into the end zone for a touchdown.

Holder Matt Johns handed the ball off to wide receiver Miles Gooch on the ensuing extra point, and Gooch converted for two points. It upped Virginia’s lead to 22-0, and Johns was greeted on the sideline by a chest-bump from London.

At that moment, at least, it seemed as if nothing could go wrong. Until it did.

“It don’t mean too much when you don’t play four quarters,” Parks said. “It all goes down the drain.”