He may have come in as a substitute but he was able to score one goal for Norway. It might not seem much for non-football fans but those who are fond of football are aware of just how crucial it is to score a goal.
There are some games wherein both teams are not able to score anything because it is hard. When Ole Gunnar Solksjaer entered, he was able to score the only goal for Norway at that game. The game ended in a draw but it was enough to make people notice the player that was only a substitute in the beginning.
The great goal start of this player was followed by three more consecutive goals in other games. People have become familiar with him and his name because of his accomplishments.