OTTAWA — Just one game into his NHL career and Auston Matthews has already made his mark.

The No. 1 overall pick in the 2016 draft became the first player in NHL history to score four goals in his regular-season debut as his Toronto Maple Leafs fell to the Ottawa Senators 5-4 in overtime on Wednesday night in the season opener for both teams.

"It was pretty surreal, I couldn't believe it," said Matthews, who had no idea he had made history with his performance.

Maple Leafs head coach Mike Babcock, who has been with Toronto for a season, was impressed by Matthews' performance. Although the Maple Leafs took the loss, he sees a lot of potential in his young team.

"For me, from my perspective, since I've been a Leafs coach that's the best night we've had since I've been here by 10 miles, not even close," said Babcock. "Now we have an opportunity."

Just as impressive was Matthews taking responsibility for Senators forward Kyle Turris scoring the overtime winner.

"That last play was 100 per cent my fault," said Matthews. "We came here to win and we didn't get that done."

It's that mentality that makes the rookie all the more impressive to his coaches and teammates.

"He's a man," said Babcock. "He's 19 years old, but he acts like he's 27. He's got good maturity.

"He's a good player. When you see that second goal he scored not many guys can do that."

Matthews's success was no surprise to Senators head coach Guy Boucher who coached against the young centre last year in the Swiss Elite League.

"He's the real deal," said Boucher. "I told everybody and I saw it first hand last year so I'm not surprised. He's the total package. He played against men last year and he's playing against men now so I'm not surprised."

Fellow Toronto rookie William Nylander benefited the most from Matthews's performance, earning two assists, while Frederik Andersen stopped 25 shots for the Leafs (0-0-1). Babcock was quick to praise fellow youngsters Mitch Marner, who had six shots on goal, as well as Zach Hyman and Nylander.

Bobby Ryan, Erik Karlsson, Derrick Brassard and Turris, with two goals, scored for the Senators (1-0-0). Craig Anderson made 34 saves.

Anderson won't soon forget the evening as he will forever be tied to Matthews in the history books.

"I'll be remembered for one thing for a long, long time in Toronto," said Anderson. "I didn't know (the four goals are a record) but I do now.

"He's good. It's one of those things he had a great night as an individual, but as a group we found a way to win. Hats off to him, he was an outstanding player (Wednesday)."

Matthews opened the scoring at the 8:21 mark of the first period, standing in front of Anderson as Hyman centred the puck from behind the net. Matthews swatted at the pass, giving Toronto a 1-0 lead on his first shot of the game.

Ottawa tied the game midway through the period as Ryan picked up Karlsson's rebound and backhanded it past Andersen. Two minutes later, Karlsson gave the Senators a 2-1 lead after scoring from the blue line.

For his second goal, Matthews showed off his flashy puck-handling skills. He stripped Ottawa right-winger Mark Stone of the puck near the Senators' blue line, then dangled the puck in and around the rest of the defence before putting it over Anderson's shoulder.

While each goal was significant, Matthews admitted the second was probably the most special as it exemplified the type of player he wants to be in this league.

He completed the hat trick just 1:25 into the second period, taking a cross-ice feed from Leafs defenceman Morgan Rielly as the Toronto veteran charged toward the goal line, putting a light one-timer past Anderson.

Despite a bipartisan crowd of 17,618 on hand at Canadian Tire Centre, hats came raining down and Matthews's mother, Ema, was spotted with tears in her eyes. Matthews' father Brian was also on hand for the game and the two were clearly emotional watching their son.

"It's pretty special having my parents here," said Matthews. "It was great to have them share the moment with me."

Brassard, an Ottawa native acquired in the off-season for Mika Zibanejad, tied the game 3-3, as he muscled his way to the net and beat Andersen short side.

Matthews added his fourth goal in the final seconds of the second period, taking a pass from William Nylander on a 2-on-1 opportunity. Matthews is the fifth player in NHL history to score a hat trick in his regular-season debut and the first in Maple Leafs history.

The 19-year-old from Scottsdale, Arizona, is the 12th first overall pick to score in his NHL debut.

Matthews was the fifth player with three goals in his NHL debut since 1943-44 and first since Derek Stepan with the New York Rangers in October 2010. Alex Smart (Montreal, 1943), Real Cloutier (Quebec, 1979) and Fabian Brunnstrom (Dallas, 2008) also had hat tricks in their first NHL games, though Cloutier played five seasons with the Nordiques in the WHA before that.

Turris, who had tied the game early in the third, had his second goal of the night 37 seconds into overtime to hand the host Senators the victory.

Notes: D Thomas Chabot and LW Matt Puempel were healthy scratches for the Senators. ... D Frank Corrado and Roman Polak as well as C Seth Griffith were healthy scratches for Toronto.