Roma midfielder David Pizarro aimed a swipe at Cristiano Ronaldo in the wake of the Giallorossi's 2-0 home defeat to Manchester United on Tuesday. The high-flying Ronaldo hit the opener for United, scoring his 36th of the season, but Pizarro was intimidated by the Portuguese's showboat tricks, despite admiring his talents. "There is no doubt that he has quality, but it is also true that he has a big head," the Chilean said after the game. "Some of his little tricks in the middle of the pitch were unnecessary and he needs to show some respect to his opposition. "You can bet that we will have something to say about it in the return leg." Roma will be facing an uphill battle when they visit the Premiership champions for the second leg at Old Trafford, bearing in mind last season's 7-1 hammering.