It's a tough game to predict as I am not sure what to expect from Roma. Leverkusen will play their high speed football and try to score at all cost. That's just how they work and they are not the kind of team that would try to play down the clock and take a draw. Roma, however, is probably going to adjust their game to whatever happens. If they score quite early in the game, I think they will try to slow down and destroy Leverkusen's game rather than focusing on their own game. If they could achieve a win with just a goal difference, they would definitely take it and play the typical Italian style in the second leg. Hopefully they don't score early as it's no fun to watch these games when Italian teams are parking the bus.