PointMe.To/Soccer recommends Click here for BigSoccer!

The 4-5-1 lineup is usually used later in a game, when a lead or a tie need to be saved over time.

Here are some details about the positions:

Sweeper (SW) The sweeper should be a leader on the field. Controls the defense, always staying behind the fullbacks.
Stopper (ST) Responsible for marking (or covering) the center forward or center midfielder of the other team. Also has an important offensive part of distributing the ball to the midfielders
Left/Right Backs (LB/RB) Mark the opponent's forwards and are the only real defenders. These players have to be dependable and willing to give up any kind of offensive play.
Left/Right Defenders (LD/RD) Mark the opponent's forwards. More advanced teams these players are used to carry the ball up the outside with the mid-fielders, allowing more effective crossing.
Left/Right Midfielders(LM/RM) With the 4-5-1, outside midfielders need to take charge and demand the ball more than usual. With only one forward, offensive plays have to be played over the outsides, since a 5 man midfield can hardly push up fast enough to support the single forward.
Center Midfielders (LC/CM/RC) Even though offensive plays should be played over the outsides, quick passes through the middle can be an effective tool. If at least two of the center midfielders are fast enough to perform a counter-attack, they can easily involve the forward into this play and either win time or go for the goal.
Forward (F1) The single forward will have to cope with a game with few chances to score, since this formation is usually used to hold the ball and win where offense is ranked only second. The forward will also have to fight for every ball in the offense and do a lot of running. A substitute should be brought into the game should the 4-5-1 be performed over a longer period of time.