That's when Red Sox right fielder Mookie Betts knew.
"Jackie does this little thing where, midway, while the ball is in the air, he starts timing it," said Betts, who hit a two-run homer and also scored Boston's third run on Sunday night to help the Red Sox win 3-0 and split their doubleheader with the New York Yankees.
"Once I saw him start timing it, I figured he had a chance to catch it. He made it look easy," said Betts, who had three hits in the night game but was happy to join the cheers for Bradley. "It made the hair stand up on my arms."
David Price (5-2) struck out eight in eight innings, and Bradley went over the bullpen wall to rob Judge and send the Yankees to their first shutout of the season.
A day after the teams played 16 innings over 5 hours, 50 minutes, they spent another long day at Fenway Park and ended the four-game series the way they started: with the Yankees trailing the first-place Red Sox by 3 1/2 games in the AL East.
It was also 3-0 in the nightcap when Judge, the winner of the All-Star Home Run Derby, came up with a runner on first and launched one toward the 420-foot marker in center. Bradley stalked it, and at the last moment leaped against the wall that juts out from right-center to pull the ball in.
"I just hit it to the wrong part of the park and the wrong center fielder," said Judge, who failed to reach base for the first time in 43 games. "Jackie's been making plays like that for a long time."
The sold-out crowd gave a huge cheer, and another after Matt Holliday struck out to end the inning. The Red Sox gathered at the edge of the dugout steps to congratulate Betts - with Price pushing his way through to thank him.
"It was special," Bradley said. "It was electric. It was just a fun moment to be a part of."
Price allowed seven hits. One night after giving up a tying homer in the ninth to send the game into extra innings, Craig Kimbrel pitched the ninth for his 24th save.
Masahiro Tanaka (7-9) gave up three runs on eight hits in 7 2/3 innings, striking out nine. The Yankees are the last team in the majors to be shut out.
"We probably gave one away and we stole one," Yankees manager Joe Girardi said. "They got one off our closer, and we got one off their closer."
Betts homered over the billboard above the Green Monster, his 17th of the year, with one out in the third inning to end Boston's scoreless streak at 24 innings. He made it 3-0 when he singled to lead off the sixth, took second on an error by second baseman Starlin Castro, third on a groundout and scored on Dustin Pedroia's second hit of the game.
Sabathia (8-3) made his second start since a stint on the disabled list (strained left hamstring). He walked five and struck out three to improve to 4-0 in his last five road starts.
Judge, who has 30 homers, got an infield single on a dribbler to the pitcher in the seventh, ending a 0-for-15 slide. Aroldis Chapman tossed a one-hit ninth for his ninth save.
In the makeup of an April 25 postponement, the Red Sox hit just four balls out of the infield and extended their scoreless streak to 22 innings.
Rick Porcello (4-12) gave up three runs - one earned - and nine hits in six innings. The 2016 AL Cy Young winner leads the major leagues in losses despite making his 17th consecutive start of six innings or more.
CAN I GET A WITNESS?
"Highlight-reel catch against probably the most notarized power guy in the game, and timely. A big catch to the deepest part of the ballpark preserved the shutout at that point. He came up big." - Red Sox manager John Farrell.
New York had not won back-to-back games since a season-high, six-game spurt from June 7-12, going 7-19 before winning Saturday and in the first game Sunday.
The Red Sox stranded 10 runners and went 0 for 11 with runners in scoring position in the opener. They went 1 for 7 in the late game, leaving them 3 for 38 with RISP in series and 3 for 58 against the Yankees this season.
Yankees: RHP Michael Pineda was transferred to the 60-day DL while he seeks a second opinion on whether he needs Tommy John surgery.
Red Sox: RHP Blaine Boyer was put on the 10-day DL with a strained right elbow. He left Saturday after pitching an inning and warming up the next.