Johnson suffered a fractured right femur in Washington's 12-6 loss and was taken to New York Hospital Queens, where he was scheduled to undergo surgery. The surgery was to be performed by Dr. Peter Dzenis, with assistance from team physician Dr. Ben Shaffer.
"He's hurt pretty bad," manager Frank Robinson said. "Nick's not going to stay down if he's not hurt that badly. When he wasn't moving, we knew he was hurt pretty bad."
The play took place in the bottom of the eighth inning, with the Mets leading at the time, 10-5. Facing reliever Jason Bergmann, David Wright lofted a soft pop fly into shallow right field.
Johnson raced back from first base, looking over his shoulder as right fielder Austin Kearns rushed in. Neither player called for the ball, which dropped to the turf as both Johnson and Kearns slid, colliding and creating a spray of sunglasses, caps and gloves.
The ball was eventually picked up by second baseman Jose Vidro in right field. Vidro's first reaction after the crash was to cover his ears, having heard a crack or pop in the collision, followed by Johnson's screams of anguish.
"I was like, 'Oh my God,'" Vidro said. "My stomach got really bad right there. It's really a tough situation for Nick and the ballclub."
Center fielder Nook Logan saw the play develop and was able to hear the same sounds from his position.
"I was yelling, 'Look out!'" Logan said. "I saw Nick and Kearnsie going after the ball, and I heard a snap. I stopped and didn't even want to go over there. What can I do? Just call out the trainers."
"It's unfortunate, but it's not something you can control," Robinson said. "It's one of those freak accidents. You're going after a ball that's hit into no-man's land, and unfortunately, it had to come out of it with that type of injury."
While Kearns rose to his feet quickly, Johnson was in limited motion for several minutes as trainers attended to the injury, attaching a splint to Johnson's lower right leg.
A white medical cart was brought onto the field, upon which Johnson was lifted and driven through the right-field bullpen gates for medical transport. Players from both teams looked on as Johnson bit into a towel, helping to quell what appeared to be tremendous pain, while the Shea Stadium crowd gave Johnson a standing ovation.
"It's unbelievable to see a teammate and a friend on the ground, yelling in pain," Kearns said. "I kind of got sick to my stomach."
"It was very tough on everyone out there," Robinson said. "He was in constant pain. When they tried to move him, I can't even describe the sound."
Play resumed with Wright on third base, as Robert Fick replaced Johnson at first base and George Lombard replaced Kearns, who was shown on television with tears running down his face as he headed for the dugout.
Mets manager Willie Randolph opened his postgame press conference by saying a prayer for Johnson's quick recovery. Kearns and third baseman Ryan Zimmerman were among the Nationals players who planned to visit Johnson at the hospital on Saturday evening.
"You just treat him normal, try to make him laugh and show that we care about him," Zimmerman said.
The 28-year-old Johnson was one of Washington's key offensive contributors this season. In 148 games, he batted .288 with 23 home runs, 46 doubles, 77 RBIs and 10 stolen bases.
"He was having a great season," Robinson said. "It's unfortunate it had to end like this."
Bryan Hoch is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.