Spanish title-holders Atletico Madrid kick-off their Champions League campaign with a home game against Porto on Wednesday.
Diego Simeone's side remain unbeaten four games into the new La Liga season, sitting in third place, level on points with city rivals Real Madrid and Valencia with 10 points.
On Sunday, Atletico came from a goal down to win 2-1 at Espanyol, with France midfielder Thomas Lemar scored a dramatic winner deep into injury time
This summer has seen Atletico re-sign striker Antoine Griezmann on loan from Barcelona, with a view to a permanent move, and he was training with his Altletico teammates at the Wanda Metropolitano Stadium on Tuesday.
Opponents Porto, meanwhile, also sit third in the in Portugal's Primeira Liga table having won three and drawn two of their five games so far. They are four points behind leaders Benfica, who have a 100 per cent record.
English Premier League side Liverpool take on AC Milan at Anfield in the other Group B game on Wednesday.