Judgment Night

Francis (Frank) Wyatt (Emilio Estevez), along with his brother John (Stephen Dorff) and friend Mike Peterson (Cuba Gooding, Jr.) set out to see a professional boxing match in Chicago with their friend Ray Cochran (Jeremy Piven), who is testing out a lavish RV.
Stuck in traffic, Ray decides to make up for lost time by exiting the expressway and search out a shortcut through a poor residential neighborhood. The four friends are alarmed when they hit a man named Teddy (Michael DeLorenzo), who they take into the RV. They find that he has been shot, and that he has a paper bag filled with money. The group sees a police car and begins pursuing it.
They are unable to catch up and their RV is side-swiped by a Cadillac. The impact forces them into a narrow alleyway, leaving the RV stuck between two brick walls and unable to start. Moments later, three unknown men shatter the back window and drag Teddy out. Still inside the RV, the four friends witness gang leader Fallon (Denis Leary) shoot and kill Teddy. Fallon reminds the gang that policy is to leave no witnesses. As the criminals approach the RV, Frank sets it on fire, and all four escape through the front window.
The four friends hide and try to outrun the gang until they think they have gotten away. They head to a railyard, followed by Fallon and his gang. While hiding inside the car of an old train, Frank and his friends are blackmailed by homeless men living in the train, who threaten to alert their pursuers to their location unless they pay them. The friends comply, but one of the homeless men freaks out when Mike won't give him his jacket. Fallon and his gang are leaving the railyard when they hear shouting coming from the railcar. As they open the car everyone aboard jumps off and starts running. Fallon accidentally shoots a homeless guy (who he thought was Mike by the jacket), but recovers Frank's wallet and now knows where he lives.
The guys find an apartment building with an open door and run inside. A local boy on the swingset outside of the building spots the guys, who then runs off to tell his friends. The group of local kids, who are protecting their neighbourhood, confront Fallon and his gang, believing them to be the group they are looking for. Fallon pays the group off to find out which building they ran into. While inside the building, Frank and his friends hole up in the apartment of two women and a child and they call the police. Fallon and his gang terrorize the building's tenants. Hearing this, the women demand that Frank and his friends leave, suggesting that they head to the roof to escape. Mike, John, and Frank manage to cross over to the neighboring building with the use of a ladder bridge. Because of Ray's fear of heights, he decides to throw the ladder down and stay behind to pay Fallon off. However, Fallon loses his patience with Ray and pushes him off the roof, falling to his death.
Escaping into the sewers, Mike suggests that they fight back against their pursuers. Sykes (Peter Greene), Fallon's best friend and right-hand man, catches up with them, and after a brief confrontation is shot and killed by Mike. Frank chooses not to risk their lives anymore, so they escape from the sewer and keep running. Within the sewer, the remaining members of Fallon's gang find the body of Sykes. A comment made by one of the gang members annoys Fallon and he (whether accidentally or not) drowns him.
Searching for help, the guys find a swap meet and Mike breaks a window in the hopes it will trigger the alarm and bring the police. Shortly afterwards, they realize that Fallon has found them once more. The last remaining member of Fallon's gang, Rhodes (Everlast) is shot dead by Mike, but in the process Mike is shot in the stomach. John goes to help Mike but Fallon shoots him in the leg. Frank leads the wounded Mike and John to a bathroom closet where they hide. Frank gets to the security office and activates a silent alarm. Knowing that the three can run no longer, Frank draws out Fallon, leading him away from Mike and John. After a struggle, Frank pushes Fallon off the stairs, causing him to fall to his death. Afterwards the police arrive, and Frank takes them to where his friends are. The movie ends with Mike and John being wheeled away by the medics, the police investigating the scene, and Frank's wallet being recovered by an officer, who then informs Frank that his wife is outside.

Question: Who is Fallon's best friend?
Answer: Sykes