Atletico Madrid battled to a 2-0 win against Salzburg thanks to a goal in each half from Mario Hermoso and Yannick Carrasco to secure a place in the Champions League knockout stages.
Diego Simeone's side beat Salzburg 3-2 in the reverse fixture - their only Group A win prior to Wednesday - and needed just a point from the trip to Austria to advance.
Salzburg started strongly as they went in pursuit of the win needed to progress at Atleti's expense, but Hermoso's header against the run of play proved the game's big moment.
Mergim Berisha and Enock Mwepu hit the post either side of that effort, while Dominik Szoboszlai squandered a glorious chance, but Carrasco volleyed in a late second to ensure Atleti will join Bayern Munich in Monday's last-16 draw.
Berisha cut inside Stefan Savic and curled a low shot against the base of the post 113 seconds into the game as Simeone's men survived a number of early scares.
Sekou Koita was played in behind but failed to beat Jan Oblak with his weak attempt, and the visiting goalkeeper did well to turn Szoboszlai's precise shot past the post.
The chances kept on falling Salzburg's way, with Patson Daka firing over at the end of a counter, but Atletico soon grew into the game and led after 39 minutes.
Carrasco sent in a flat inswinger and Hermoso flicked the ball on, the final touch coming off the defender's shoulder for his first goal since March 2019 when still an Espanyol player.
A Salzburg leveller would have made for a tense finale but Szoboszlai placed the ball wide of the post after being played clean through on goal and Mwepu hit the upright from a long way out, the visitors restricted to shots from range by that point.
Atleti then wrapped things up with four minutes to go as Angel Correa picked out Carrasco at the back post on the counter to fire a crisp first-time shot away from Cican Stankovic.
What does it mean? Job done for Atletico
The LaLiga leaders have been in impressive form domestically but have failed to fire on all cylinders in Europe, this just their second win in six Group A matches.
Atleti were pegged back late on by a weakened Bayern side last week to leave their hopes of progression in the balance, but they did what was required in Salzburg.
The visitors scored from their only shot on target in the first half and, despite having just 42.2 per cent of the ball overall, saw things through to reach the knockout rounds for the seventh time in eight seasons under Simeone.
Yan the man
Carrasco sent in a delightful delivery for Hermoso's opener and then rounded off the scoring late on to make certain of the victory, the Belgium winger scoring and assisting in a Champions League game for the first time in what was his 41st appearance.
He may have lost possession more times than any other Atletico player (24), but it was his passing and finishing that ultimately helped to make the difference on the day.
Oblak stands firm against profligate Salzburg
The home side created countless opportunities, the best of which fell the way of Szoboszlai early in the second half - one of 18 shots they managed.
Szoboszlai failed to convert when one-on-one with Oblak, who did at least have two saves to make. He now has 28 clean sheets in the competition since making his debut in September 2014, which is one more than next-best Marc-Andre ter Stegen over that stretch.
Key Opta Facts
- Atletico have progressed from the group stage in seven of their eight Champions League campaigns under Simeone, with 2017-18 the only season they suffered elimination in the group stage.
- Salzburg have only won one home game across their three Champions League campaigns (D3 L5), with that lone victory coming in September 2019 against Genk (6-2) - courtesy of an Erling Haaland hat-trick on his debut in the competition.
- Atleti are unbeaten in their past 14 Champions League games when they have scored the first goal (W11 D3), with their most recent defeat after opening the scoring coming in September 2017 versus Chelsea.
- Hermoso's opener was his first ever goal for Atletico in what was his 35th appearance for the club across all competitions.
- Carrasco was directly involved in both of Atleti's goals (one goal and one assist), ending a run of 18 consecutive appearances in the competition without scoring or assisting (since his goal versus Rostov in October 2016).
Salzburg have a top-of-the-table clash with leaders LASK in the Austrian Bundesliga on Sunday, while Atletico travel to city rivals Real Madrid in three days' time.