The Buffalo Bills' roster took a hit on Tuesday when left guard Richie Incognito announced that he was retiring.

Incognito, 34, has been the Bills' best offensive lineman since rejoining the team in 2015. During his second stint, Incognito started all 48 games with the Bills and was named to the Pro Bowl in all three seasons.

Replacing Incognito won't be easy. Buffalo has some internal options on the roster. Two names to watch are Ryan Groy and John Miller.

Groy is expected to compete for the starting center job with Russell Bodine, but he could compete for the left guard job if Bodine wins the center job. Last season, head coach Sean McDermott was asked about the possibility of Groy playing guard.

"Ryan does some good things and the important part for Ryan is that he does back up Eric as well at the center position," McDermott said last year. "Ryan does give us some flexibility both at center and as well as at guard."

Miller is the likeliest option currently on the Bills' roster. The offensive guard only appeared in four games for the Bills in 2017. One reason Miller saw little action was due to a lingering ankle issue.

As it stands, here is a look at the Bills' unofficial depth chart for 2018.

Buffalo Bills 2018 Unofficial Depth Chart - Regular Offense STARTER 2ND 3RD 4TH WR Kelvin Benjamin Andre Holmes Rod Streater Quan Bray TE Charles Clay Nick O'Leary Logan Thomas Khari Lee/Keith Towbridge LT Dion Dawkins Conor McDermott Josh James LG John Miller Adam Redmond C Ryan Groy Russell Bodine RG Vlad Ducasse RT Jordan Mills Marshall Newhouse De'Ondre Wesley WR Zay Jones Brandon Reilly Malachi Dupre Kaelin Clay QB AJ McCarron Nathan Peterman FB Patrick DiMarco HB LeSean McCoy Chris Ivory Travaris Cadet Marcus Murphy/Taiwan Jones/Aaron Green Base 4-2-5 Defense STARTER 2ND 3RD 4TH LDE Trent Murphy Shaq Lawson Eddie Yarbrough Cap Capi LDT Star Lotulelei Adolphus Washington RDT Kyle Williams Rickey Hatley RDE Jerry Hughes Marquavius Lewis Terrence Fede Owa Odighizuwa SLB Matt Milano Ramon Humber Julian Stanford WLB Tanner Vallejo Xavier Woodson-Luster CB Lorenzo Alexander Deon Lacey SS Tre'Davious White Phillip Gaines Lafayette Pitts FS Micah Hyde L.J. McCray SS Jordan Poyer Rafael Bush Kelcie McCray Dean Marlowe CB Vontae Davis Breon Borders Special Teams STARTER 2ND 3RD 4TH K Stephen Hauschka P Colton Schmidt Cory Carter H Colton Schmidt PR Kaelin Clay KR Taiwan Jones LS Reid Ferguson

Buffalo has internal options to replace Incognito, but may opt to sign a free agent or draft an interior offensive lineman in the 2018 NFL Draft.