East Lyme — Stationed alone in front of the Avon goal, senior Wes Williamson collected a pass with time running out in a Class M boys' lacrosse quarterfinal thriller on Saturday.

Then Williamson dropped the ball, adding even more suspense to the moment in a deadlocked state tournament game.

Williamson never panicked, quickly recovering and firing in the game-winner with three-tenths of a second left, setting off a wild celebration that started on the turf field and continued near the bleachers where the deliriously happy East Lyme fans joined in the fun from their spot in the stands.

"It was nuts," Williamson said. "These fans are crazy so I just went and tried to give them a high five as I went off. It's like what Dwyane Wade used to do in the NBA."

A second celebration erupted when the game ended, as the top-seeded Vikings (16-0) rallied multiple times to earn a dramatic 13-12 victory and advance to the semifinals for the first time since 2009. They'll play host to No. 4 Weston on Wednesday at 6 p.m.

Weston knocked off No. 5 Watertown, 6-5.

Williamson smartly snuck behind the defense, which had eyes on senior Ryan Whaley who held the ball up top. Whaley alertly spotted Williamson.

"Whaley hit me with a pass and I dropped it at first, but I picked it up," Williamson said. "I knew there was no time left, so I just shot it and it went in."

While Williamson was the hero and finished with a team-high five goals, he had plenty of help from his teammates. Junior Anthony Gesino chipped in three goals and an assist, Whaley had two goals and three assists, junior Sean McCusker added two goals, junior Zach Boguszewski scored a goal and senior Matt Valakos three assists.

Coach Gary Wight, who was on the receiving end of a water bucket bath after winning the ECC Championship, returned the favor by dousing his team during the post-game celebration.

Wight praised his Vikings for their character.

"I can't ask more of these guys," Wight said. "They're just a great group of kids. I'm proud of them. They work hard in practice. Every game they give what they have. The heat got to a couple of guys and we lost a couple during the game. It's just the next guy up. We're a team."

East Lyme trailed for most of the state tournament game, including 5-1 early on and 8-5 at halftime.

The Vikings remained patient and chipped away at the deficits. They also took advantage of the mistake-prone Falcons who were whistled for 11 penalties compared to just one for the home team.

"Second half, we made some adjustments and both the offense and defense stepped it up," Wight said. "We talked about at halftime playing one possession at a time rather than looking too far ahead."

Eighth-seeded Avon carried a 10-9 lead into what turned out to be a wildly entertaining, intense fourth quarter.

East Lyme answered with two straight goals — one by Williamson and the other by Whaley — to take its first lead since 1-0, holding an 11-10 edge with 9:09 remaining.

Then Avon seized the momentum, scoring twice in less than three minutes for a 12-11 lead.

The Vikings refused to buckle, as Gesino's rocket tied the score with 5:19 left. They got the ball back and called timeout with 47.5 seconds remaining.

It looked like the game was headed to overtime when Whaley found Williamson who put the finishing touches on a masterpiece of a tournament win.

"That's the character of this team, we never give up," Wight said. "We fight until the end, the last second."

Now the Vikings are on to the semifinals. They lost to Darien, 16-4, in their last trip there in 2009.

"It's huge," Williamson said of reaching the semifinals. "We know we have a lot of work to do because those teams are all great. But we're going to come in ready to play."

g.keefe@theday.com