Atletico Madrid coach Diego Simeone hailed an "enormous effort" by his side after they began Champions League Group D with a hard-fought 1-0 win at PSV Eindhoven.
Saul Niguez's fine volley shortly before half-time was enough to decide an open game in which last year's UCL finalists were just barely the better side against a team which had pushed them to penalties in the last 16 in the 2015-16 competition.
PSV rued an early Luuk de Jong header ruled out for a debatable push, a dubiously awarded penalty taken by Andres Guardado saved by Atletico keeper Jan Oblak, and a much clearer spot kick missed by the English officials when Diego Godin handballed at a corner.
Speaking to BeIn Sport after the final whistle, the Colchoneros coach admitted his team had been forced back at times but a "enormous" team performance was enough to take the three points.
"We knew it would be difficult," Simeone said. "They are a team who work hard and we saw that last season. They had their plan and stuck to it, as they did last season.
"They caused us problems and kept pushing until the end. In the second half we did not manage to kill the game on the break, but the lads played a tremendous game, and it's a good win."
Simeone said there was plenty for his side to improve upon, such as not being able to take a second half chance on the break, as they had in winning 4-0 at Celta Vigo in La Liga last weekend.
"We want to keep working, we know we have a lot to improve," he said. "We have made an enormous effort, a third consecutive away game for us, after Vigo and Leganes. We are going home happy for the result, although it's a pity we could not end the game quicker on the break, as we did the other day at Celta Vigo."
In Group D's other game Bayern Munich beat Rostov 5-0 at home, with the Bundesliga side next up for Atletico at the Estadio Vicente Calderon in a fortnight's time.
"Bayern at home will be difficult," Simeone said. "They are a big rival. But we will enjoy for now the enormous effort we put in today."
Goalscorer Saul said after the final whistle that keeping a clean sheet had been the key to eking out the important result.
"We have got a very good win, we worked very hard, it was difficult first game in the Champions League," Saul said. "We're very happy with this good win. They have good fans here. In the second half it was more difficult for us, they managed to push us back, we could not get out.
"But we did well, as we often do, keeping a clean sheet which was very important. The first game in the group is always important. So we are very happy, and thinking now about moving on to the next game."