In any game with a fixed time duration, leading in the earliest part of the game can say little about whether a competitor is winning.
This can also be illustrated when the leader is the only one that has had an opportunity to score, or the leading team is about to turn over its scoring privilege and thereby give the opponent a chance to overturn the score. This can happen in baseball, where the teams may be close in score and the leading team goes to the outfield in the top of the ninth inning.
Another example occurs in a relay race, where the anchor runner (the last runner) on a team is known to be especially good and likely to overturn race.
In an election, ballot counting may show a bias toward one candidate in the early counts, showing that candidate is leading. But knowing something about the uncounted precincts can lead a knowledgable poll watcher to know that leading is not necessarily winning.
In cases like these, leading does not necessarily equate to winning.