Having just won the main position in the team, Runalson could miss at least one or two games with a head injury.
After joining Leuven on loan from Arsenal to compete in the first division, Runarson had to wait for his own opportunity. He also made his debut on the new team until 27 October and did not make his league appearance until 26 November.
Since then, the goalkeeper has gradually won the main position, starting 5 games in 5 games in all competitions. But now it looks like this momentum could end prematurely.
Lunalsson's most recent start was against Bruges, but was substituted for a head injury just before half-time.
The 26-year-old goalkeeper leaned over to save the ball from the feet of opposing striker Noel Lang, whose knee hit Runnarsson's head.
The Iceland international received treatment on the field but still felt dizzy and was replaced and taken to the hospital.
Runarson became the third of Arsenal's three goalkeepers on loan to be injured, with Illyev and Tom Smith already sidelined for some time with injuries.
The two players have not played since October 2 and coincidentally they were injured on the same day.
Now that Runnarsson has joined them, it's not a good time for him. Leuven will face Brugge again in the Belgian Cup quarter-finals on Sunday and again next Tuesday.
For now it looks like the Arsenal goalkeeper will not be playing in either of these games.