Their side had a tricky away game without their leading goalscorer, Radamel Falcao — 'el Tigre.' They travelled to an Espanyol side without a win so far in the league, a club where attendances are on the slide and fans are beginning to turn against those in charge, from the directors to the coach.
Espanyol have to sell their best players season after season and they've made some baffling decisions to get rid of coaches who'd helped their youth system become one of the best in Spain, but their decline is still mystifying. They were fourth at the start of February, but they've since won one in 17, picking up just eight points from 48.
None of which was of concern to the small pocket of Atleti fans at Cornella on Sunday, waving their Spain flags in Catalonia and wondering if their side would be toothless without their injured tiger.
Falcao is La Liga's seven-goal top goalscorer ahead of Lionel Messi and Cristano Ronaldo so far this season. The 26-year-old Colombian finished third last season behind the more feted pair, with 24 league goals (and 12 more in Europe) in his first season in Spain after his 40 million euro (plus extras) transfer from Porto.
Could Atleti overcome claims that they're a one-man team by winning a tough away game? It was Atleti's worse performance of the season, but they still managed a 1-0 victory to make it 18 games unbeaten. The victory pushed the Rojiblancos to second in the table with five wins and a draw from their opening six league games.
These are good times for the team who sit fifth in the all-time Spanish league table. Had they not been run so erratically in the last 30 years, they may have been closer to Valencia in third and Athletic Bilbao in fourth, but instability is the norm at the Vicente Calderon. Such is Atleti's historical financial profligacy, only Barca and Madrid have bigger debts, while the club's two most important personnel often contradict each other, two opposites who don't attract, but nevertheless have been drawn to Atletico like so many others.
Payments for Falcao are behind schedule and UEFA withheld their prize money from last season as Atletico had bills outstanding. They're a loss-making club and given the increasing limitations of their funds, spent just 1m euros in the summer, while selling players for 18m euros.
Atleti continued to bring players in, most of them on loan. Chelsea's excellent goalkeeper Thibaut Courtois successfully replaced David de Gea and has stayed for a further season, while attacking midfielder Raul Garcia, on a stint from Osasuna, has excelled even when played out of position.
Atleti's tough financial circumstances — almost all of them self-inflicted — have thus failed to impact on the pitch. And things couldn't be better where it matters to their fans. Atleti, who are Spain's third best supported club with average crowds of 44,105 last season, topped off their second Europa League success in three seasons in May by hammering Chelsea in the European Super Cup in August. When Falcao got a first half hat-trick, world football took notice and began to wonder where he'd be going next for an astronomical transfer fee.
Strikers have long been cherished at Atleti and they have a fine record of either developing their own like Fernando Torres (though Atleti fan Raul slipped the net) or signing the right emerging talents, from Sergio Aguero to Hugo Sanchez and Christian Vieri. They joined a club with a history of prolific front men like three times Pichichi winner Garate, Paulo Futre and Diego Forlan.
Things started to click with the appointment of Diego Simeone late last December. Like legendary boss Luis Aragones, Simeone is a much loved former player. He replaced Gregorio Manzano when the team were 11th having lost Aguero, De Gea, Jose Reyes and Elias and Forlan in the summer of 2011.
Atleti conceded 19 goals in the eight league games before Simeone; they didn't concede a goal in their first six games under him at the start of 2012. Simeone manages like he played: with a tough defensive discipline.
With his defence sorted, his midfield coached by the sublime former Valencia star Ruben Baraja and his attack led by a player he calls "irreplaceable", Atleti's rise continued to the end of the season when they finished fifth, a more impressive statistic given they also played 19 European games on the way to winning the Europa League.
Falcao's Asturian striker foil Adrian was the only player to start in all 19. Adrian, who broke into the Spain set- up before the Euros, didn't cost a penny from Deportivo La Coruna in 2011.
Atleti have had a winning start in their defence of the Europa League, playing a near reserve team to beat Hapoel Tel Aviv 3-0. A similar side is expected to play Victoria Plzen on Thursday, showing their strength in depth.
While the season is young, they're looking good for a first top-three league finish since they won the title in 1996. Then again, we're talking about Atleti, a club noted for their instability and unpredictability, a club who've seen expectations destroyed time and time again.
They will face many challenges, not least on Sunday as they entertain third-placed Malaga who are also undefeated. That game is played immediately after the clasico. If Barca fail to win and Atleti continue to prosper with their tiger back, then they'll go top of the league.
Andy Mitten will be blogging for us on all matters in La Liga throughout the season. He contributes to FourFourTwo, the Manchester Evening News and GQ magazine amongst other publications.