No. 46 soon will be No. 17.

The Yankees, a team source confirmed Sunday night, plan to retire Andy Pettitte's number this season, making his uniform number the 17th retired by the club.

The ceremony will take place Aug. 23 at the Stadium before the Yankees' game (time to be determined) against the Indians. Pettitte also will receive a plaque in Monument Park that day.

Pettitte, who went 219-127 in two stints with the Yankees -- the lefthander pitched for the Astros from 2004-06 -- retired after the 2013 season, going out along with Mariano Rivera. Pettitte is the second of the Core Four to have his number retired, following Rivera's No. 42.

Pettitte, 256-153 overall and baseball's all-time leader in postseason victories with 19, won five World Series titles with the Yankees and was a three-time All-Star.

One of Pettitte's sons, Josh, broke the news on Twitter late Sunday afternoon.

"Heard it here first," he wrote. "Yankees are making August 23rd Andy Pettitte day. Retiring #46 and honoring him with a plaque in Monument Park!!"