Hating the Haters
Head over to the jogging area. Follow Bernie but keep your distance until he reaches the tunnel. After Bernie gets battered, chase his attacker up the stairs. He will flee in a Faggio. Steal one parked on the left side of the road and chase him. Do your best at shooting him. An SMG is recommended. If you're having a hard time taking him down, just keep following him. Bernie will eventually wait at the entrance you came through at the start of the mission. Pick him up and continue catching up on the attacker. After neutralizing the attacker, go to the end route marked on the map.
Union Drive
After watching or skipping the cutscene, on the very left of where you are standing is a very fast sports car and is a must have. Get in it, pick up Bernie and follow the yellow marker on the map. After watching the cutscene, chase after two of Dimitri's thugs. Keep up with them and try to avoid running into the flipping cars dashing at you. As soon as Dimitri's thugs crash their car, park up near their wrecked car and take them out as they run away. Sometimes the police will come after you during this. If they are alerted, get back in the car with Bernie, evade the cops and return to Bernie's place.