After that, the reigning two-time NHL MVP repeatedly helped his teammates pad the margin.
The five points were a season high for Ovechkin. He scored his 29th goal with only 49 seconds elapsed to get the Capitals off to a quick start during their third game in four nights, then assisted on Washington's next four goals.
"Just lucky moments," Ovechkin said. "We got a lot of chances; I was there."
Ovechkin loves scoring goals. But regardless of who puts the puck in the net, he will celebrate just the same.
"He enjoys the team scoring goals," coach Bruce Boudreau said. "Whether he gets an assist or whether he gets nothing, when the team does well, he does well."
The scoresheet deemed that Ovechkin took only two shots, but his name was stamped all over the scoring summary.
"It seems like he'll get 10 shots on a night and not get anything, and then tonight it's just every other chance you get [you score]," Knuble said.
Both of Knuble's goals came in the second period, boosting the Capitals' lead to 4-0. He has five goals in his last five games.
After coming off the bench for an ineffective Michal Neuvirth in Washington's previous two games, Theodore started what he finished in a fine performance against the NHL leaders in shots on goal.
Tomas Kaberle scored on the power play for Toronto. The Maple Leafs have lost five of six overall and five straight on the road.
Toronto has struggled to score this season, but on this night the blame lay on the defense, which was powerless against Ovechkin and the Caps.
"It just shows their skill level. They scored on just about every chance they had," coach Ron Wilson said.
Leafs forward Jamal Mayers said, "Obviously, we gave [Ovechkin] too much time and space. He's one of the most dynamic players in the league, and if we give him that much time, then he's going to make a play."
Vesa Toskala, who blanked Philadelphia just 24 hours earlier in Toronto, yielded a goal on the first shot he faced and fell to 7-10-2.
Ovechkin opened the scoring with a wrist shot from the right circle after taking a pass from Nicklas Backstrom. It was one of only two shots on goal by the Capitals in the first 12 minutes.
Washington went up 2-0 with 2:09 left in the period. After Ovechkin broke his stick on a slap shot from a few feet inside the blue line, Eric Fehr swept the slow-moving puck past Toskala for his career-high tying 12th goal of the season.
Early in the second period, after Toronto's Francois Beauchemin hit the post with a shot, Ovechkin went the other way and took a shot. The puck ended up in the crease, and Knuble tapped it into the net.
"Sometimes you just happen to look down and it's right there," Knuble said.
Knuble's second goal came after Toronto defenseman Ian White dipped his stick into the crease behind Toskala to bat away a shot by Ovechkin. But Knuble was there for the rebound.
Kaberle ruined Theodore's shutout bid with a blast from inside the blue line with 1:23 left in the period.
Ovechkin got his final assist with 13:13 remaining and Washington on the power play. After the Capitals won the draw, Ovechkin rifled a shot that was deflected by Tomas Fleischmann past Toskala for a 5-1 lead.
Tom Poti completed the scoring with 8:54 left.
Capitals D Brian Pothier was scratched because of an unspecified injury. To fill the void, the Capitals recalled John Carlson from Hershey of the AHL. ... The teams split four games this season. ... Mike Green had two assists for Washington, extending his points streak to seven games. ... Of Kaberle's team-high 40 points, only five are goals.