Veteran forward Blaine went down with a broken left collarbone during his second shift as the Bandits beat the Rock 14-10 in National Lacrosse League action.
Manning hurt his shoulder in a corner scrum.
"He'll be out six to eight weeks," said coach Troy Cordingley. "We're going to miss him but we’ve got to move on."
It was 3-3 after one quarter, Toronto led 6-5 at halftime and Buffalo was up 10-8 going into the fourth quarter.
Toronto outshot Buffalo 56-40 so it wasn't as if Cordingley's players were outclassed. Bandits goalie Mike Thompson was outstanding, while Rock netminder Matt Roik remained winless with his new team.
"I liked our effort here," Cordingley said. "There was a four-minute span where we were awful and they scored four goals because we made bad lacrosse decisions.
"Offensively, I thought we had a lot of quality shots. Thompson played extremely well for them and we had some tough luck around the net with some crossbars and posts. That’s the way it goes. It's January. We're not done."
Rock captain Colin Doyle wants to stay positive despite losses to Calgary and now Buffalo.
"It was better," he said of the team's effort. "I think we played well enough to win that game.
"In a lot of aspects we outplayed them but we had a brain fart in the third and let them get on a run. We couldn't regain the lead. That's the game of lacrosse for you. I'm not going to focus on being 0-2. I'm going to focus on: Are we getting better?
"Game 1 was a real disappointment. We didn't show up. We didn't go to battle. Tonight, we made some mistakes that cost us. I don't like the 0-2 but I'm going to stay away from that and just say we were putting a better effort together."
Buffalo got three goals from Luke Wiles, two from each of Mat Giles, Kevin Buchanan and John Tavares and one from each of Steve Priolo, Chad Culp, Tracey Kelusky, Mark Steenhuis and Scott Self in its season opener in front of a First Niagara Center crowd of 16,356.
For Tavares, the 43-year-old Bandits forward who holds all of pro lacrosse's all-time scoring records, the goals were his 800th and 801st in regular season and playoffs combined. Tavares, into his 21st season, also picked up six assists.
For Toronto, Doyle scored three goals and Kasey Beirnes, Sandy Chapman, Garrett Billings, Dan Carey, Glen Bryan and Bill Greer got one each.
Toronto was up 6-4 when Buchanan scored a short-handed goal for the Bandits 61 seconds before halftime. With Chapman and Mike Hobbins both checking Buchanan and trying to whack the ball out of his stick, the slippery American scooped the ball between Roik's legs as he was falling into the crease to make it 6-5.
Kelusky tied it in the opening minute of the third quarter with a power-play goal, Steenhuis put the Bandits up 7-6 and Self made it 8-6 with Buffalo’s fourth consecutive goal.
Then came a splurge of four goals in 41 seconds — Doyle and Greer for Toronto and Wiles and Giles for Buffalo — and the Bandits were up 10-8.
Wiles supplied the Bandits' finishing touches by scoring two power-play goals early in the fourth to make it 12-8 after Ryan Sharp was assessed a major penalty for high sticking.
"It was a great night for us, a great first win," said Wiles, who was acquired during the off=season in a trade with Washington. "We're going to be jockeying for position in the East all season so we need to win these games within the division.
"Our goalie played awesome, our offence stepped up and got goals when we needed them and our defence was swarming them all night. The pace is a lot faster with the new rules so you have to think fast. I thought we outthought them and we wound up getting the win."
Thompson's most extraordinary save came as he was falling and thrusting his stick into the air hoping to get lucky and stop a Carey shot towards a half-empty net. He got lucky. The outcome was far from decided at that point.
"I totally bit on his fake," Thompson said. "But I was able to get the stick up and I was fortunate enough that he put (the ball) right in there."
It was the goalie's first game since tearing knee ligaments in the championship game of the 2011 world indoor tournament in Prague last May.
"I won't be 100 per cent for a couple of years — that’s what the doc told me," he said. "But I feel strong and confident. It feels great right now."
Buffalo didn't have any exhibition games before opening its season.
"I was little worried this morning because I hadn't played since last May," he said. "But I was able to settle down after the first couple of shots. I felt right back at home. We’d been beating the heck out of each other for the last couple of months so it was good to get some fresh meat to roll over on."
Coach Darris Kilgour said Thompson "played one of the best games I’ve seen him play as a Bandit."
"If it wasn't for Mikey Thompson and the goal posts, it would have been a completely different game,’" Kilgour said.
Notes: Toronto D Drew Petkoff has been on injured reserve and will like be activated to take Manning’s roster spot . . . Priolo, a six-foot-five defenceman from St. Catharines, was playing his 24th pro game and his goal was the first of his three-year career . . . D Bruce Codd and D Bill Greer made their Rock debuts after sitting out the opener with what the team described as ``lower body injuries’’ . . . Toronto deleted Rob Hellyer, Jamie Rooney and Jesse Gamble . . . Buffalo scratched Frank Resetarits, Tom Montour and Roger Vyse . . . Amazing staying power: when Mat Giles stepped onto the floor in a Bandits uniform for the first time Saturday, it was the 12th NLL franchise that he’d played for since entering the league with the Rock in 1999. ``A lot of those teams folded,’’ says Giles. ``It’s part of being in the NLL.’’ . . . Toronto had been 12-6 in regular-season games in Buffalo before losing this one . . . Next opponent for both teams is Rochester. Buffalo is at Rochester next Saturday and the Knighthawks are in Toronto on Friday, Jan. 27.