BOSTON -- Baseball's greatest rivalry has been officially ratcheted up. Now the fans are part of the action, too.
It'll be days, if not weeks, before Boston police determine whether a crime was committed at Fenway Park Thursday night. But this much is certain: the near-brawl between Gary Sheffield and the fan who allegedly struck the right fielder in the eighth inning has strained relations between the Yankees and Red Sox.
While Joe Torre was quick to say, "we're not mad at the Red Sox" he harshly criticized Boston fans who he felt were responsible for provoking Sheffield.
"These people shouldn't be allowed to walk the streets much less come to a ballgame," the manager said. "The sad part about it is it's a handful of people screw it up for the people who just come to watch a ballgame."
This isn't the first time the Yankees have taken issue with the hostility in and around Fenway. Two years ago, team president Randy Levine cited the Sox for the "lawlessness" in the ballpark, which club officials believe led to relievers Jeff Nelson and Karim Garcia brawling with a member of the grounds crew.
Nelson and Garcia were charged with assault, ultimately cutting a deal that called for 50 hours of community service. That fight, however, was confined to the bullpen and fans, as decidedly anti-Yankee as they might have been, were still innocent bystanders.
But with Sheffield now the first casualty of the more dangerous playing field, it's anyone's guess how the Yankees or Red Sox will react the next time a foul ball drifts into the stands.
As Sheffield himself said, "it's just a baseball game. You don't expect to get hit in the mouth."
What made matters worse is that immediately after the final out, as a handful of Yankees trudged back to their dugout after a failed bases-loaded rally, a fan slipped by security and sprinted down the third base line.
It turns out he had no intention of attacking the Yankees and was merely making a drunken attempt to slide into home plate. He was quickly overpowered by cops, handcuffed and arrested. But as one Yankee player said, "who knew what the guy was thinking?"
Historically, opposing players have enjoyed the charged atmosphere inside Fenway, unique in how close the fans are to the field. But Red Sox officials have also worked to corral that energy: vendors no longer hawk beer in the stands, and there's a two-beer limit at the concession stands.
The Yankees have been similarly concerned about their fans' behavior, deploying riot police onto the field after Games 6 and 7 of last year's AL Championship Series against Boston.
Still, there's little that can be done to thwart a determined fan, as was the case Thursday night. Sheffield was too busy following the trajectory of Jason Varitek's triple as it rolled along the base of the wall in right, unaware of the fan's arm draping over the edge.
Whether the contact was deliberate or accidental will be determined by police. Even though the Yankees hurriedly left Fenway for a charter flight to Baltimore, they were informed that a police investigation will begin shortly, and Sheffield will be asked to replay the events that nearly led to a brawl.
He'll likely tell the cops what he told reporters: he was punched in the mouth, threw his hands toward the fan to create enough space to throw the ball back to the infield, and then contemplated a retaliation.
Even though he considered himself provoked, Sheffield stopped before reaching the stands.
"Ron Artest was the first thing that came to my mind. Don't react," Sheffield said, referring to the Indiana Pacers' star who was handed a season-long suspension from the NBA for fighting with fans back in November.
"It could've been worse, but I held my composure. I thought about the consequences," Sheffield said.
Time will tell whether this rivalry can possibly become any more volatile. Expect security at Yankee Stadium to be heavy over Memorial Day weekend, when the Sox and Yanks next meet in New York for three games. And Fenway should be similarly policed in mid-July when the Yankees return to Boston.
But sooner or later, players from both teams will be alone in the field, no doubt remembering what happened to Sheffield. Before chasing a foul ball, the Yankees and Red Sox may very well pose the rivalry's new pressing question:
Am I really safe?
Bob Klapisch is a sports columnist for The Record (N.J.) and a regular contributor to ESPN.com.