They may have to prove it again on Monday night, too.
Both Jeter and Rodriguez were not listed in the lineup posted about three hours before the first pitch of Monday's Orioles-Yankees game. Jeter is dealing with a painful bruise on the top of his right knee cap and Rodriguez continues to be bothered by a sprained left thumb.
Manager Joe Girardi didn't sound optimistic that he'd have either Jeter or Rodriguez on Monday when he spoke to reporter's after the Yankees' 8-3 win on Sunday night.
"Hopefully neither one of them will be out very long. But I don't know if we'll have either one of them tomorrow," said Girardi, adding that Rodriguez's lingering thumb injury was a "concern." "If they can play, they can play. My sense is from watching both of them they're not going to be able to."
In the first game of Sunday's doubleheader, Jeter fouled a ball off of his right knee in the third inning. He hobbled around the home plate area momentarily and was checked on by Girardi and team trainer Gene Monahan.
Jeter remained in the game -- a 2-0 Yankees' loss -- and was slated to lead off and play shortstop in the second game of Sunday's doubleheader.
But his knee began to swell between games and became, in Jeter's words, "a challenge."
He was scratched minutes before the first pitch.
"It was really bizarre to be quite honest with you," said Jeter, who admitted he was nervous when the injury started to swell after ice was applied.
Jeter underwent an X-ray which came back negative. "He's gimping around," Girardi said.
He was hopeful to play on Monday but admitted that the knee was "sore" after the game.
Rodriguez also played the first game for the Yankees, playing nine innings at third base. Girardi said before the game that he wasn't going to play the former AL MVP at third in the nightcap because he'd missed two games earlier in the week due to the thumb injury. Turns out, the manager didn't have the opportunity because Rodriguez wasn't healthy enough to play at all.
"His thumbs bothering him so we just felt it wasn't in our best interest to play him either," Girardi said. "We need to get him healthy."
Rodriguez missed games Tuesday and Wednesday last week with the thumb ailment, which he suffered diving for a ball last Sunday in Minnesota.
He returned on Thursday and snapped a 96 at-bat homerless streak on Friday before going 0-for-4 in the early game on Sunday.
Rodriguez is batting .289 with 14 homers and 53 RBIs. Jeter has come on strong after struggling earlier in the season. He's hitting .296 with 69 runs scored and 48 RBIs. Since coming off the disabled list on July 4, the Yankee captain is batting .348.
Eduardo Nunez replaced Jeter at short on Sunday and Eric Chavez took over for Rodriguez at third. Both Nunez and Chavez are penciled in at the same positions in the lineup posted before Monday's game.
Ian Begley is a regular contributor to ESPNNewYork.com.