EDEN PRAIRIE, Minn. — It's turning into quite a year for Vikings centers.

The Vikings on Tuesday announced they have extended the contract of center John Sullivan in between Mick Tingelhoff's January induction to the Pro Football Hall of Fame and his enshrinement scheduled for Aug. 8, which will fall on Sullivan's 30th birthday.

Two weeks later, Sullivan and his wife are expecting their first child. He said they decided not to learn the child's gender ahead of time.

"We're going to be surprised," Sullivan said during a phone interview. "We can't wait."    

Sullivan said the couple escaped some of the barrage of snows that hit his home state of Connecticut with trips to Miami and California and attended the NFL Players Association meetings in Hawaii. They are scheduled to fly back to Minnesota this week, and he plans to return to Winter Park for a workout on April 13, a week before the team is scheduled to open its offseason workout program. He's looking forward to the reunion with teammates.

"When you're away for a few months, you start to miss the camaraderie of the locker room," Sullivan said. "I'm excited to get back around guys that share that same experience of playing in the NFL. I'm excited to see who's been working out, guys getting healthy. We had a number of injuries in our room last year, so I'm excited to see all the guys. It's a great time of year."

The extension adds another year onto the two that remained from the five-year contract that Sullivan signed in December 2011. Sullivan joined the Vikings in 2008 after he was drafted out of Notre Dame in the sixth round. He backed up Matt Birk and also learned from veteran left guard Steve Hutchinson as a rookie and became the Vikings starting center in 2009. Sullivan has missed just three starts in the regular season since.

Sullivan started all 16 games in 2014, pushing his career totals to 93 starts in 109 regular season games. He is the sixth Vikings center to play in 100 career games. Tingelhoff leads the franchise with 240 starts and career games at the position.

"I want to start by saying thank you to the Minnesota Vikings for putting their faith in me as a person and football player," Sullivan said in a press release. "The Vikings have been with me through professional highs and lows, and have stood by my side and supported me through personal hardships. My ability to express the true depth of my gratitude comes from my actions on and off the field.

"I intend on doing absolutely everything I can to ensure we attain our ultimate goal of a Super Bowl championship on the field, and that I live my life in a way that is commensurate with that championship standard off the field," Sullivan continued. "One of the most exciting aspects of signing this extension is the trajectory of the organization. We have a talented roster, a state of the art facility on the horizon and the best fan base in the NFL. After a year with Coach Zimmer at the helm, I couldn't be more excited about our team's future. Now, it falls on us as players to fulfill our potential and to execute and I intend on making sure that happens." 

The Vikings continued a recent philosophy of retaining multiple starters and draft picks before they hit the free agency market. Minnesota similarly extended right guard Brandon Fusco and tight end Kyle Rudolph, who were both selected in 2011, before the 2014 season.

Sullivan helped solidify an offensive line that used **five different starting combinations** because of injuries last season. He and Matt Kalil were the only two starters to make all 16 games.

After Fusco went down in Week 3, he was replaced by Vladimir Ducasse until Week 7 when reserve tackle Mike Harris filled in. Veteran Joe Berger moved into the starting lineup at right guard in Week 8.

After four more games, right tackle Phil Loadholt suffered a torn pec in November that was similar to Fusco's September injury. They've been encouraging each other while **rehabbing** this offseason. Charlie Johnson also missed a pair of starts at left guard late in the season because of injury, and he was replaced by Ducasse.

Johnson and Ducasse finished their contracts with the Vikings, so a different player will be on Sullivan's left this fall. The Vikings reached a deal to bring back Berger, and reserve guards David Yankey and Austin Wentworth are also on the roster.

Sullivan said he's maintained communication with Fusco, Loadholt and Kalil and was glad to hear that Berger agreed to a deal to return to Minnesota.

"That was huge," Sullivan said. "He let us know as soon as they agreed to terms, and Joe's such a great player. He can fill so many spots, and obviously we have a little bit of a question mark with what's going to happen at left guard. We all thought a year ago that Joe was completely capable of stepping in and doing a great job. It's nice to have him back almost as an insurance policy along the offensive line."

Although he is "sad to see Charlie go," Sullivan said he will help the Vikings next left guard.

"He's a close friend of mine. I'm wishing him nothing but the best in the future," Sullivan said. "I think he's got some great football left in him and some other team will be lucky to have him, but it's exciting. Obviously, there's the potential I'll be playing next to a younger, inexperienced player and I'll just try to coach them up the way I was coached up when I was a younger player in this league, show them the right way to do things, work in conjunction with the coaches, teach them about the game of football, point out certain things and hopefully make sure they don't have to deal with the learning curve too much and be a resource for them in any way possible."