The Tampa Bay Mutiny forward, snubbed in voting by fans, earned MVP honors by scoring two goals and adding an assist to help the East defeat the West 9-4.
Diallo, the league's leading scorer, entered the game in the second half and sparked the East's outburst of six unanswered goals. Both of his goals and the assist came between the 59th and 65th minutes.
East coach Octavio Zambrano of the MetroStars selected Diallo for the game.
"I feel proud," Diallo said. "But maybe today I showed that the voting system should be changed."
Some MLS players and officials were upset because the league's top three scorers were bypassed in the fan voting.
Diallo broke a 4-4 tie 14 minutes into the second half after chasing down a pass by Mutiny teammate Carlos Valderrama and beating West goalkeeper Zach Thornton.
Two minutes later, Diallo took another Valderrama pass and dribbled around Thornton on a breakaway to put the East up 6-4. Diallo then assisted on Jay Heaps' goal in the 65th minute.
"Diallo is not only about power and strength," Zambrano said. "He is a flashy player who likes to do other things and have fun with the game. I definitely think he is one of the best."
Valderrama, a former star of Colombia's national team, had four assists in the second half. Valderrama leads the league with 19 assists and received the most All-Star votes.
The standing-room crowd of 23,495 at Columbus Crew Stadium didn't have to wait long to see a goal.
Clint Mathis put the East up 1-0 in the second minute off a pass from MetroStars teammate Mark Chung.
The West came back to take a 3-1 lead after Chicago's Ante Razov, who has scored three goals in his last four games with the U.S. national team, scored in the 17th and 22nd minutes off passes from Los Angeles' Cobi Jones.
Kansas City's Preki was credited with an assist on Razov's first goal, making him the only player to get a point in all five All-Star games. In between Razov's goals, Jones assisted on a give-and-go play with Mauricio Cienfuegos, who scored in the 19th minute.
The West took a 4-3 lead just before halftime when Peter Nowak scored off Jones' fourth assist.
"We came out in the second half and pretty much fell apart," Preki said. "We had few chances early on but didn't score, and it looked like every time they went down the field, they scored."
Columbus teammates Dante Washington and Brian McBride scored the game's final two goals.
The East has won three out of four All-Star games against the West (a team of U.S. All-Stars beat a team of MLS players from other countries in 1998).
Saturday's total of 13 goals topped the scoring record set last year, when the West won 6-4.
With plans t expand by two teams in 2002 and existing teams looking for cozier venues, the MLS selected Crew Stadium, its only soccer-specific site, for the All-Star game in hopes of inspiring other teams to plan similar projects.
"Our goal is to try to build as many stadiums like this as we can and push our investor-operators to recognize that it will work if you build it," league commissioner Don Garber said.
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