(CNN) -- Manchester City manager Roberto Mancini warned Mario Balotelli about his behavior after the striker's on-pitch antics during Sunday's preseason friendly against Los Angeles Galaxy.
Balotelli gave City a 1-0 lead from the penalty spot before going clean through on goal after 28 minutes -- but his extravagant pivot and back-heel shot ended embarrassingly with the ball rolling harmlessly wide of the goal.
Mancini reacted by replacing the 20-year-old former Inter Milan forward with midfielder James Milner, and the Home Depot Center crowd voiced their disapproval of Balotelli's actions as the Italy international left the field.
"We need to be always professional, always serious," the 46-year-old Mancini told a post-match news conference. "In this case, Mario wasn't professional and for this, I made the change."
Balotelli, who joined City from Inter in August 2010, was visibly unhappy with his withdrawal and threw a water bottle to the floor in frustration, refusing to go to the dressing room before the halftime break.
But Mancini said the matter was now closed, and that he hoped Balotelli would learn from the experience.
"Mario is young. Sometimes he makes a mistake, but I am there because I want to help him always," he said.
"For me, it's finished now ... I hope it is a lesson and I hope he can understand this."
Balotelli suffered with disciplinary problems during his debut season in England's top division, receiving a red card in only his third Premier League appearance and picking up a further six yellow cards.
He seemed to suggest he thought the offside flag had been raised when he wasted his first-half opportunity against the Galaxy, but Mancini dismissed that claim.
"Mario is Italian," the former Lazio coach said. "He's street-wise. Mario knows that he wasn't offside."
American Mike Magee leveled for the Galaxy in the second half with a long-range looping volley over Joe Hart, but the English FA Cup winners won the match after a penalty shootout in which the City goalkeeper scored the decisive goal to make it 7-6.
Meanwhile, City striker Carlos Tevez has dismissed Manchester United manager Alex Ferguson's claims that he will retire in two years.
Ferguson said Tevez told his former club United in 2009 that he intended to quit the sport within four years, prior to completing a move to archrivals City.
"He told us at the time of negotiations that he was only going to play for four more years," the 69-year-old said in quotes reported by Britain's The People newspaper.
"So if we had signed him on a five-year, contract knowing that he was going to quit in four years' time, there is no re-sale value for us."
Representatives of the Argentina star rejected Ferguson's claims and said the 27-year-old planned to play on for several years.
"At no time did he discuss retiring with the Manchester United management, and Mr. Ferguson has not mentioned this at any time before," said a spokesperson for Tevez.
"In fact Carlos feels he is capable of playing for a further eight years and though he has been in the form of his life, he feels he is only going to get better in the coming years."
Tevez saw a move back to Brazil and former club Corinthians fall through last week, and has been heavily linked with a move away from the Etihad Stadium since having a transfer request rejected in December 2010.