Betances -- the Yankees' No. 2 prospect -- tossed three no-hit innings, while fellow right-hander Warren -- No. 10 on MLB.com Top 20 list -- scattered two hits over four scoreless frames in the team's 4-4 tie against the Boston Red Sox.
Starter Warren struck out three batters and retired the final seven men he faced. He surrendered a pair of second-inning singles before retiring Kelly Shoppach to strand runners on the corners.
In three previous spring appearances out of the bullpen, Warren had given up two runs on six hits, a walk and a hit batsman over 5 1/3 innings. Thursday's start lowered his ERA to 1.93.
Betances was just as effective if not quite as sharp in his fifth Grapefruit League outing. He fanned four batters and walked three in three innings of relief to maintain his perfect 0.00 ERA.
In eight innings of preseason work this spring, the 6-foot-8 hurler has allowed five hits and five walks. He has struck out six batters.
New York native Betances made his Major League debut against the Tampa Bay Rays in September, and former fourth-rounder Warren posted a 3.60 ERA in 27 starts with Triple-A Scranton/Wilkes-Barre and was named to the International League midseason All-Star team in 2011.
C.C. Sabathia, Hiroki Kuroda, Ivan Nova, Michael Pineda and Phil Hughes are expected to start the year in the rotation, although Freddy Garcia is also in the mix for a spot.
Top prospect Manny Banuelos looks less likely to start the year in the Majors after being reassigned to Minor League camp in the team's first round of cuts Friday. Thirty-nine year old Andy Pettitte also adds to the potential pitching logjam after signing a non-guaranteed $2.5 million contract with the Yankees last week.