(Reuters) - The Cincinnati Reds' championship hopes were dealt a blow on Wednesday as injured pitcher Johnny Cueto was removed from the National League Division Series roster, making him unavailable unless the team reaches the World Series.

Cincinnati, which leads the best-of-five divisional series 2-1, will replace Cueto with right-handed pitcher Mike Leake, Major League Baseball (MLB) said in a statement on Wednesday.

Cueto, whose 19 wins were the third most in the National League during the regular season, left his team's playoff opener versus the San Francisco Giants on Saturday with a back injury.

The 26-year-old ace of the Reds' starting rotation threw eight pitches for six strikes and registered a strikeout before leaving in obvious pain during the first inning of the game, which Cincinnati won 5-2.

Leake, who went 8-9 with a 4.58 earned-run average during the regular season, will start Wednesday's 4 p.m. ET (2000 GMT) game for the Reds.

Should the Reds advance, they would play either the St. Louis Cardinals or Washington Nationals in the best-of-seven National League Championship Series (NLCS).

In accordance with MLB rules, Cueto is ineligible to return in the NLCS, but would be eligible to return for the World Series if the Reds advance.

(Reporting by Frank Pingue in Toronto; Editing by Gene Cherry)