Atletico Madrid boss Diego Simeone says he is learning more than ever this season and expects another examination of his managerial abilities from Arsene Wenger.
The Rojiblancos were drawn against Arsenal in the Europa League semi-finals on Friday having narrowly ousted Sporting CP in the previous round.
The 2-1 aggregate victory put them within touching distance of a third appearance in the competition's final in the space of nine seasons, Simeone having masterminded victory in 2012.
But, amid a campaign where Simeone is "learning most about being a coach", the 47-year-old is braced for a difficult battle with Wenger.
"With their history they are a very strong rival," Simeone said of the Gunners.
"They have a very important coach who is very capable with plenty of experience and quality footballers.
"We know English football and at home they are very strong. It is a 50-50."