Line-up lock is one of the main features on FanDuel that differentiates it from daily fantasy football rivals such as DraftKings. It simply means that you cannot make changes to your fantasy football squad after the contest has begun.
On FanDuel, your line-up will be locked as soon as the first game in your chosen contest has kicked off, whereas on some of the other daily fantasy football sites you can continue to make changes to your team even after some matches have started.
Line-up lock is a more important factor in some American sports, such as NBA, where it is very common to see extremely late changes made to a team, so it is less likely to be a factor for daily fantasy football players, unless one of your stars suffers an injury in the warm-up, for example.
Many users feel that line-up lock is fairer as it helps to level the playing field, while it also leaves players free to get on with their day as soon as they cannot change their teams. Again, this is particularly pertinent for American sports, as there can be a large time difference between kick off in the first east coast match and the start of the final west coast match on any one day.
When playing FanDuel it is therefore more important than ever to select players who you are confident are going to be in the starting line-up for their teams.
Line-up lock is also sometimes used as a term to describe a player who you feel you have to pick in your team.
For example, Manchester City striker Sergio Agüero may be considered by some people to be a line-up lock for a Premier League daily fantasy football game, while a La Liga daily fantasy football line-up lock could be Barcelona forward Luis Suárez.