Diego Simeone's side enter the game having claimed a 2-1 win over Espanyol in La Liga action at the weekend, while Porto played out a 1-1 draw with Primeira Liga champions Sporting Lisbon.
With a long-awaited Spanish top-flight crown now in the trophy case, Atletico will endeavour to translate that domestic dominance into success on the continental stage, and they have already started as they mean to go on this term.
After taking seven points from their first three La Liga fixtures before the international break, Atletico returned to action against Espanyol on Sunday and marched to a hard-fought 2-1 success, with Thomas Lemar netting a dramatic winner nine minutes into second-half injury time following previous strikes from Yannick Carrasco and Raul de Tomas.
Atletico may not have looked all that convincing in any of their four La Liga games so far this term, but they sit level with Valencia and Real Madrid at the top of the rankings before they begin their journey to what would be a first-ever Champions League title this year.
The 2021-22 season marks Atletico's ninth consecutive stint in the group stages of the Champions League, but they have failed to make it past the last 16 in three of the past four seasons and were sent packing at that point by eventual champions Chelsea last year.
However, that 1-0 loss to Chelsea on home soil in the first leg represents their only defeat from their last 14 Champions League matches on home soil, and seven of Atletico's last 11 European meetings with Portuguese sides have seen them emerge victorious.
Porto's stronghold on the Portuguese football scene was brought to an end by Sporting Lisbon in the 2020-21 season, and Sergio Conceicao's side sought to claim an early scalp over the newly-crowned champions during Saturday's highly-anticipated battle.
Sporting attacker Nuno Santos took just 16 minutes to open the scoring on the day before Porto's Luis Diaz rescued a point for his side in a 1-1 draw, but both teams have now fallen four points adrift of early pace-setters Benfica, who boast five wins from five and have taken advantage of their rivals' slip-ups.
League fortunes aside, Porto prepare for action in the 2021-22 Champions League aiming to make the knockout rounds for the fifth time in six seasons, although a group comprising Atletico, AC Milan and Liverpool does not exactly spell optimism for Conceicao's side.
Porto can at least boast a 15-game unbeaten run in all competitive matches since their first-leg defeat to Chelsea in last year's quarter-finals, and the Champions League regulars can take solace in the fact that they have prevailed in four of their last five away games in the group stage.
Atletico claimed 2-0 and 2-1 victories over Porto during the group stage of the 2013-14 tournament - where they fell short to Real Madrid in the final - but the Portuguese side did claim a memorable 3-0 win at the Vicente Calderon in 2009, where Radamel Falcao netted against his then-future club.
Atletico have no concerns whatsoever to deal with on the injury front for the opening day, but centre-back Stefan Savic is suspended after seeing red against Chelsea and reportedly using abusive language towards an official.
Lemar has firmly put himself in contention for a start after his heroics against Espanyol, so Angel Correa's spot may be at risk after he lasted just 45 minutes of the weekend's encounter.
Conceicao took Bruno Costa and Ivan Marcano off in the first half against Sporting, but the Porto coach affirmed that these were tactical decisions after both players picked up early bookings in the encounter, although he then witnessed substitute Toni Martinez pick up two bookings in two minutes to be sent for an early bath.
Atletico Madrid possible starting lineup:
Oblak; Gimenez, Felipe, Hermoso; Trippier, Koke, Llorente, Lemar, Carrasco; Suarez, Griezmann
Porto possible starting lineup:
Costa; Mario, Mbemba, Pepe, Marcano; Otavio, Uribe, Oliveira, Diaz; Corona, Taremi
We say: Atletico Madrid 2-0 Porto
The loss of an experienced head in Savic is obviously a bitter blow for Atletico, but their ability to grind out narrow results when it matters most is almost unparalleled.
Porto have started the Primeira Liga season in ideal fashion but will struggle to break down a typically robust Simeone defence, so we can only back Atletico to get off on the right foot here.