Sidney Crosby was playing the best hockey of his life. Now his extraordinary year is on hold and no one is sure when he will be back on the ice. The Penguins said Monday that their superstar center was diagnosed with at least his third concussion just a few days before the defending Stanley Cup champions open their season. Crosby, 29, finished as a Hart Trophy finalist last season, won the Conn Smythe Trophy as playoff MVP, and led Team Canada to the World Cup of Hockey title just a few months after winning his second Cup with the Penguins. Coach Mike Sullivan said Crosby was concussed in practice Friday and that there was no timetable for his return. Sullivan declined to reveal how the concussion happened, but said Crosby was not discouraged or frustrated by diagnosis.

Flames extend Gaudreau

The Flames and rising star Johnny Gaudreau agreed to a six-year contract extension. The $40.5 million deal has an annual salary cap hit of $6.75 million. Gaudreau, the 23-year-old former Hobey Baker Award winner from Boston College, had been a restricted free agent since his entry-level contract expired July 1. The forward ranked sixth in the NHL in scoring last season with 78 points . . . Former Bruins forward Gregory Campbell was waived by the Columbus Blue Jackets as NHL teams pare down to their opening night rosters. Jets goaltender Ondrej Pavelec and Islanders forward P.A. Parenteau were also waived . . . Forwards Gabriel Bourque and Rene Bourque — no relation — each signed a one-year deal with the Colorado Avalanche. Gabriel Bourque’s deal is a two-way contract, meaning he still has to clear waivers . . . Left wing Lauri Korpikoski signed a $1 million, one-year contract with the Stars after the eight-year veteran was released from his professional tryout with the Flames.

COLLEGE FOOTBALL

Big Ten is large in AP Top 25

In the latest Associated Press Top 25 poll — released a day later than usual because two FBS games were played Sunday — the Big Ten placed four teams in the top 10 during the regular season for the first time since 1960. No. 8 Wisconsin and No. 10 Nebraska joined No. 2 Ohio State and No. 4 Michigan among the first 10 teams. Alabama remained No. 1, receiving 56 of 61 first-place votes. No. 24 Western Michigan is ranked for the first time in school history.

BC sets kickoff for Oct. 22

Boston College announced a 12:30 p.m. start time for its Oct. 22 game against Syracuse at Alumni Stadium . . . No. 25 Navy’s game at East Carolina on Thursday night was postponed to Nov. 19 because of expected flooding from Hurricane Matthew. East Carolina is located in Greenville, N.C., and the Tar River, which runs through Greenville, is expected to crest later in the week . . . No. 9 Tennessee dismissed senior defensive tackle Danny O'Brien from the program for an unspecified violation of team rules. O’Brien, a starter, was injured in Saturday’s loss at Texas A&M . . . Arkansas sophomore linebacker Dre Greenlaw will miss 4-6 weeks after undergoing foot surgery. Greenlaw is the No. 2 tackler on the 22nd-ranked Razorbacks . . . Armand Shyne, the starting running back for No. 21 Utah, is done for the season because of a right leg injury.

LSU, Florida bicker over makeup date

LSU won’t give up a home game later this season to make up a game at Florida last Saturday that was postponed because of Hurricane Matthew, athletic director Joe Alleva said. Alleva’s stance leaves open the possibility of LSU hosting No. 18 Florida on that date and buying out its scheduled opponent, South Alabama — should the Gators be willing to do so. He said the possibility of Florida coming to LSU this season and then LSU going to Florida the next two seasons had not been discussed . . . Florida quarterback Luke Del Rio will start Saturday against Missouri, returning to the lineup after missing two games with a sprained left knee . . .

MISCELLANY

Pistons’ Jackson out awhile

Detroit Pistons guard Reggie Jackson is expected to miss 6-8 weeks with knee and thumb problems. The team said Jackson, a former BC standout, had platelet-rich plasma injections to treat left knee tendinosis and a sprained right thumb . . . Exaggerator, the winner of the Preakness Stakes and the only 3-year-old male to win three Grade 1 races this year, was retired and will stand at stud next year at WinStar Farm in Versailles, Ky. Exaggerator also won the Santa Anita Derby and Haskell Invitational at Monmouth this year. He retires with six wins in 15 starts and $3,581,120 in earnings . . . Heart to Heart led all the way to win the $200,000 Knickerbocker Stakes on the turf at Belmont Park in New York . . . The Boston University men’s hockey team moved up from fourth to second in the USCHO.com poll, receiving five first-place votes. Quinnipiac (third) and BC (sixth) each dropped a spot, while UMass­ Lowell held at eighth . . . The BC women’s hockey team is fifth in the USCHO.com poll.

Ginsburg critical of anthem protests

Supreme Court Justice Ruth Bader Ginsburg called the protests of football players who decline to stand for the national anthem ‘‘dumb and disrespectful.’’ In a wide-ranging interview posted Monday on Yahoo, Ginsburg, 83, said she had the same opinion about flag burning. ‘‘I think it’s a terrible thing to do, but I wouldn’t lock a person up for doing it,’’ she said. ‘‘I would point out how ridiculous it seems to me to do such an act.’’ Many athletes — San Francisco 49ers quarterback Colin Kaepernick among the more prominent — have received national attention for refusing to stand for the anthem this year, citing racial injustice and police brutality among the reasons. ‘‘If they want to be stupid, there’s no law that should be preventive,’’ Ginsburg said. ‘‘If they want to be arrogant, there’s no law that prevents them from that. What I would do is strongly take issue with the point of view that they are expressing when they do that.’’ . . . Belgium scored the fastest goal in World Cup qualifying history when Christian Benteke slotted home against Gibraltar after only seven seconds of play in Brussels. Benteke went on to score two more goals in a 6-0 win . . . Jo-Wilfried Tsonga won for the first time since retiring from his quarterfinal match at the US Open, beating Florian Mayer, 6-3, 6-2, in the opening round of the Shanghai Masters . . . The University of Maine said the school mascot missed a men’s hockey home game Saturday night because he was a passenger in a car whose driver was arrested en route to Alfond Arena on a drunken driving charge. The driver was a fellow student. The arrest took place at around the time the game started