Dealing with these two punks can be a bit of a pain if you aren't armed with a firearm. If you aren't, try using a knife (or your fists) to take one out at a time. If you have a firearm, however, than this fight will be much, much easier. Simply train your pistol (for instance) on one of the foes, fire away, and then do the same to the other one. Once both are slain, you'll get an onscreen prompt letting you know that Vlad is making his getaway. It's time to pursue him!
Run out of the back door (or through the front, if it's quicker for you) and get back into your car. Roman will already be in the passenger seat, so you don't have to wait around for him. Once in the car, begin following the fast-moving red blip on your HUD. This is Vlad attempting to make his getaway in his vehicle. He's pretty fast, so you're going to need to stay on top of him, but his destination is easy enough to get to if you simply want to wait for him. He's headed towards the harbor on the west side of the borough, by the Algonquin-Dukes Expressway and the Algonquin Bridge.