Bayer Leverkusen coach Roger Schmidt has praised Tottenham's Son Heung-Min before their clash in the Champions League.
Borussia Dortmund are top of their Champions League group, but with Madrid and Sporting snapping at their heels, three points are crucial in Lisbon.
Mauricio Pochettino is confident Eric Dier can play his game in different positions for Tottenham.
"It's a big plus for us [that Guardiola] knows them. He knows the team, the club, the stadium and he knows Messi," Gundogan said of Barcelona.
Tottenham forward Son Heung-Min says former Premier League stars Ruud van Nistelrooy and Rafa van der Vaart helped him to become a success in Europe.
Gladbach's Andreas Christensen has been ruled out against Celtic after picking up a gluteal muscle injury during a goalless draw with Hamburg.