Table:
text: 2011 in Norwegian football
Norwegian clubs' performance in Europe
Norwegian clubs' performance in Europe
Team Contest_and_round Opponent _1st_leg_score_ _2nd_leg_score_ Aggregate_score
Tromsø Europa League 2nd Qual. Round Paks 1-1 (A) 0-3 (H) L 1–4
Aalesund Europa League 1st Qual. Round Neath 4-1 (H) 2-0 (A) W 6–1
Aalesund Europa League 2nd Qual. Round Ferencváros 1-2 (A) 3-1 (aet) (H) W 4–3
Aalesund Europa League 3rd Qual. Round Elfsborg 4-0 (H) 1-1 (A) W 5–1

Question: What was the name of Elfsborg's team opponent in Norwegian football in 2011?