Centre Stephen Halliday scored the third-period winner, but not all the news was good on this night.

The Ottawa Senators drew first blood in the Battle of Ontario.

The Senators couldn’t have scripted a better way to start the season than a gutsy 3-2 victory over the arch-rival Toronto Maple Leafs in enemy territory at Scotiabank Arena on Saturday night.

Centre Stephen Halliday scored the third-period winner, but not all the news was good.

The Senators finished the night without top defenceman Jake Sanderson, who left after the first period, and there was no immediate update on his status.

Coach Travis Green told reporters in Toronto that Sanderson has a lower-body injury he’d already been dealing with and they’ll know more after further examination on Sunday.

“We’ll know more in the next few days, but Sandy was smart enough to pull himself early enough that he didn’t reaggravate it too badly. He just felt that it was coming and took himself out,” said Green. “That was a smart thing to do.”

Captain Thomas Chabot led the attack with a goal and an assist, while Claude Giroux had two assists. Michael Amadio also scored for the Senators, and goaltender Linus Ullmark was key, making 27 stops.

“I thought the third period was our best,” Chabot said. “We played exactly the way that we wanted to play. I’m just glad we got it done.”

After sitting idle for four days while the Leafs had already suited up for two games, the Senators used their speed and created opportunities against Toronto netminder Sergei Bobrovsky.

Halliday completed the comeback from a 2-1 deficit by chipping a rebound past Bobrovsky at 9:48 of the third. That came moments after the Senators failed to score on a power play.

The Senators held the Leafs to 1-for-4 with the man-advantage.

Already without Artem Zub to start the season, the Senators played the final 47 minutes of this contest without Sanderson. He stayed on the bench in the first period, but didn’t take a shift in the final seven minutes.

He has been dealing with an unspecified ailment, and there were questions all week as to whether he would even play in this one.

He left the final preseason game against Montreal on Sept. 26 midway through the second period. Head coach Travis Green noted it was a different ailment than what Sanderson had been dealing with a week earlier.

The TV cameras showed a frustrated Sanderson on the bench, smashing his stick after being caught up along the boards with Toronto’s Nick Paul.

“He was devastated on the bench when he told me about it,” Chabot said of Sanderson. “He’s going to put everything he can into it and he’ll be back in no time.”

That meant the Senators were forced to finish the game with only five defencemen, including rookie Carter Yakemchuk.

The Senators have turned the page with Chabot wearing the captain’s ‘C’, and the overall goal is to make the playoffs for the third straight spring.

Chabot couldn’t have gotten off to a better start in his role as captain. He became the first captain in franchise history to score in his first game wearing the ‘C’.

He opened the scoring at 18:51 of the first period by redirecting a rebound off Bobrovsky and into the net on the stick side. It was the 12th straight season that the Senators had scored first in their opener.

“It was awesome. I’m not going to lie. I never make it about myself but scoring the first one was pretty special,” Chabot said. “My parents were in the building, and it’s been a special couple of days. I’m just glad we got the first win of the year.”

In doing so, they tied a National Hockey League record held by the New York Islanders (1997-2009) and the Boston Bruins (1972-83). The last time the Senators didn’t score the first goal in an opener was Oct. 9, 2014, against the Nashville Predators.

Chabot was also taxed by playing 26 minutes and 35 seconds with Sanderson hurt. Jordan Spence was second in ice time at 22 minutes and 30 seconds.

Giroux was also strong with 18 minutes of ice time and he went 10-2 in the faceoff circle. The 38-year-old gets better with age.

The Senators need their top goalie to be the difference.

There were ups, downs and challenges for Ullmark last season, but he arrived at camp refreshed, ready and refocused. He went 14-4-3 down the stretch last season after returning from a mental health break and was at his best to help the club make the playoffs.

Ullmark, who had some help from his posts in this one, was solid. He frustrated Toronto shooters and was a big reason why the Senators were tied 2-2 with the Leafs after two periods.

A big stop by Ullmark helped set up the tying goal by Amadio in the second. Tim Stutzle took a pass from Chabot, after Chabot picked up the rebound of the save by Ullmark, and dished a slick pass to Amadio, who beat Bobrovsky on the glove side at 12:40.

“It’s fun to win on a Saturday night here in Toronto,” Ullmark said.

The Leafs pulled out to a 2-1 lead at 7:06 of the second on a power play. Kirill Marchenko scored his first in a Toronto uniform after he took a pass down low and froze Ullmark before beating him with a backhander.

Senators franchise icon Daniel Alfredsson is the power-play coach for the Leafs, so that hurt.

Ullmark had no chance on the tying goal 33 seconds into the second period by Auston Matthews. The Leafs’ captain scored his 27th career goal against Ottawa by tipping the puck home only 33 seconds into the frame.

The Senators start the regular season with three games in four nights. Next they will face the Boston Bruins on Monday at 7:30 p.m.

It’s nice to be back.

bgarrioch@postmedia.com