The upstart Boston Cannons engaged the best team in Major League Lacrosse and came up one goal short.

Midfielder Zach Runberg scored an unassisted goal with 22 seconds remaining to lift the reigning champion Denver Outlaws to a 17-16 victory over the Cannons yesterday at Quincy’s Veterans Memorial Stadium.

“I sweeped the groundball and it was a 4-on-3 so I knew we had the advantage men-wise,” said Runberg. “I just threw a pump fake to draw the defenseman over to the other guy and saw my opening and took advantage of it. “

The Cannons (3-1) suffered their first loss of the season and now will begin a tough stretch of road games at Dallas, New York and Atlanta. The Outlaws improved to 4-1 with their second victory in three nights to assume possession of first place.

“Being on the road all week will be a good opportunity for our guys to be together and play three really good teams,” said Cannons coach Sean Quirk. “Every team in this league is good and we are excited about the next challenge starting at Dallas and get back after it.”

Kyle Jackson and Mark Cockerton led the Cannons with four goals apiece. Ryan Lee paced the Outlaws with four goals while Brandan Kavanagh and Chris Aslanian netted hat tricks.

“I wouldn’t call it a setback, I’m proud of the way the team battled,” Quirk said. “They persevered through that game and it’s definitely not a setback.

“We learned a lot about ourselves tonight in some good way and that’s the best team we’ve played to date. It showed some weakness that we have to continue to work.”

Cannons midfielder Zed Williams scored at 11:58 of the fourth quarter to cut the Outlaws lead to 12-11. Denver’s response was fast and furious with three goals in the span of 1:20. Lee’s fourth made it 15-11 at 9:43 and the Outlaws appeared to be in control.

The Cannons retaliated with four unanswered goals, two by Jackson, to tie the game 15-15 with 4:35 remaining. Denver midfielder Zach Currier put Denver up 16-15 with his first with 3:41 to play. Jackson tied the game with 42.3 seconds to play.

“We were down three multiple times and our guys battled back to tie it up,” said Quirk. “They fought and when you get down by three it can go either way and we chipped away and tied it up.

“Denver played a great game offensively and defensively. We went on a run late in the fourth to tie it up. There were a lot of runs both ways tonight.”

Cockerton opened the scoring at 11:00 of the first just as the skies opened with a deluge of rain. Zed Williams found Cockerton unattended and he beat goalie Dillan Ward with a rip from 20 feet. The Cannons went up 2-1 at 7:32 when Jackson’s bad angle shot deflected in off Ward for his seventh of the season.

The Outlaws scored three unanswered goals to close out the first quarter up, 4-2. Long pole midfielder Graham Bocklett scored his first of the season on a bounce shot from 20 feet at 1:32.