But it was the league-leading Caps who showed their class on the night, cruising to a comfortable 4-1 win.
Toronto had the disadvantage of having played in Buffalo the night before (a 4-2 win) while Washington last played Sunday.
"I don’t want to make any excuses for anything. I would have liked obviously (to have) played them tomorrow and then have a measuring stick," said Toronto coach Mike Babcock, asked if the night was a measuring stick for his young team.
"To me we didn’t measure anything. We didn’t find out how good they were because we didn’t push them at all. So to me it was a one-sided game. They were better than us from start to finish. We had eight minutes or something at the start of the second (period) but other than that they were bigger, stronger, faster, quicker, more organized — better."
Mitch Marner, with his 19th of the season, added a power-play goal with 68 seconds left to deny Philipp Grubauer his fourth career shutout.
Washington outshot Toronto 38-28.
"We need to be sharper and play better," said Leafs forward Leo Komarov. "We saw how they play. We’re still a bit far away from that."
The Capitals (53-18-8) could have clinched the Metropolitan Division, Eastern Conference and Presidents’ Trophy on the night. But in addition to beating Toronto, they needed a Columbus win over Pittsburgh and the Penguins — with a 4-1 victory — weren’t co-operating.
"I thought we came out and played with purpose," said Washington coach Barry Trotz.
"The only disappointment I had is we took a late penalty and (Grubauer) didn’t get the shutout," he added. "A real good effort for us against a really good team.
"We benefited from them playing last night, I think. Them and Buffalo have a pretty good rivalry and those games are pretty intense."
The Caps, having finished their season-long five-game road trip, host the Rangers on Wednesday.
The Bruins beat Tampa Bay 4-0 to clinch a playoff spot. Toronto (39-25-15) would have joined them with a win.
The Leafs lost centre Brian Boyle during the game to an upper-body injury, which may have come from a hard first-period collision with Washington’s Wilson.
With both teams involved in back-to-back games, it was a battle of the backups: Toronto’s Curtis McElhinney versus Grubauer.
The Leafs lived dangerously in a fast-paced first period that saw the Caps spend a lot of time in the Toronto end.
Eller, on a sweet feed from Andre Burakovsky, opened the scoring at 14:34 with a shot from near the right face-off spot that took a deflection off a Toronto skate. One Capital after another was a step faster than their Leaf counterpart on the play.
Washington outshot Toronto 13-3 in a first period that saw 10 Leaf giveaways.
The Leafs came out with considerably more bite to open the second period and pressed the Washington goal. But the Caps weathered the storm and went ahead at 10:00 on the power play via a well-worked passing sequence finished by Shattenkirk, who had a lot of goal to shoot at as McElhinney was forced to move from side to side like a target in a carnival shooting gallery.
It was Shattenkirk’s 12th of the year and first as a Capital. It was also Washington’s 36th power-play goal in their last 40 games.
Alex Ovechkin got an assist on the play, moving him into sole possession of second place among Russian-born players on the NHL’s all-time scoring list. He came into the game tied with Alexander Mogilny with 1,032 points and trailing Sergei Federov by 147 points for first place.
Ovechkin has 60 of those points (33 goals, 27 assists) in 42 career games against the Maple Leafs.
Washington played a controlled third period with Grubauer mopping up when needed. Schmidt, a late replacement for the injured John Carlson (lower body), added to the lead at 8:11 coming in from the point with little opposition to snap a shot past McElhinney.
Wilson made it 4-0 with a nifty deke at 16:46 after being sent in alone by ex-Leaf Daniel Winnik.
Toronto finishes out the regular season with home games against Tampa Bay on Thursday, Pittsburgh on Saturday and Columbus on Sunday.