Though they lifted the Taca de Portugal for a 19th time in June, the Lions were pipped to top spot by Benfica, who beat them again in Wednesday's curtain-raiser; their hosts, meanwhile, are back in the top flight after just one year away.
Match preview
Returning to competitive action after a busy pre-season schedule, Benfica's first match of the 2023-24 campaign brought them head to head with old foes Benfica, in the Portuguese Super Cup at Estadio Municipal de Aveiro.
In a tempestuous encounter, two second-half strikes proved enough to see Benfica run out winners, as 12 yellow cards and two reds were issued by the referee. Despite both being old enough to know better, 40-year-old Pepe was sent off for kicking David Jurasek and Porto coach Sergio Conceicao received a red card for verbal abuse.
All of which highlights the Dragons' bitter disappointment at losing to the Lisbon giants again, having relinquished the league title to Benfica last season. Nonetheless, Conceicao and company did at least manage to secure two pieces of silverware in 2022-23 - the Taca de Portugal and the Supertaca.
They also stayed in the title race right to the last day of the season, by winning each of their last nine matches and going unbeaten through their final 12, but that was still not enough to avoid a frustrating runners-up finish.
As Porto prepare for another crack at the domestic crown and an upcoming Champions League campaign, five friendlies leading up to their Supertaca defeat brought two wins, two draws and one loss - the latter at the hands of Premier League side Wolves.
No club has retained the Portuguese title over the past six seasons, which may give heart to Porto in the months ahead, and the summer arrivals of Spanish duo Nico Gonzalez and Fran Navarro should certainly aid their cause.
Albeit at a lower level, the Dragons' first-day opponents Moreirense did manage to secure top spot last term, as they finished first in Liga 2 by a margin of 10 points.
Relegated in 2022, at the end of a season in which they tried three different managers without success and were demoted via a playoff, the club from Moreira de Conegos returned to the top tier under experienced coach Paulo Alves.
However, Alves left at the end of the season, allowing former Boavista assistant Rui Borges to take his first step in Liga Portugal management.
Moreirense now kick off their 13th campaign at the elite level, following a mixed pre-season period and last month's Taca de Liga first-round exit to Farense - a tie in which they were beaten on penalties following a 1-1 draw on home soil.
A difficult start to the league season awaits Borges's side, as after meeting Porto on Monday, Braga will be their opponents in the third round, and a visit to Sporting follows in September.
Moreirense pre-season form:
Porto pre-season form:
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Team News
As impending punishments for Sergio Conceicao and Pepe will only be handed out on Wednesday, both men are available for Porto's first league game of the new season.
Nonetheless, after Pepe was caught out for Benfica's second goal and was also sent off in this week's Supertaca defeat, his place in central defence may be under some threat.
Dismissed in last season's cup final, Wendell is back among Conceicao's options against Moreirense, having served his suspension in midweek. The left-back will battle it out with Zaidu Sanusi for selection, while Spanish signings Nico Gonzalez and Fran Navarro are also vying for promotion to the starting side.
Despite strong interest from Champions League runners-up Inter, Mehdi Taremi should continue to lead the visitors' front line; Gabriel Veron and Evanilson are set to miss out through injury.
Moreirense, meanwhile, have made a host of defensive reinforcements this summer, with one of five such arrivals being right-back Fabiano Souza, who returns to Portugal following a loan spell with Kasimpasa.
Though several players have departed since the hosts' Liga 2 title triumph, Dinis Pinto, Gilberto Batista and the experienced Marcelo - who has made 195 appearances in the Portuguese top flight - are all new contenders for Rui Borges's XI, in which Brazilian striker Andre Luis starts up front.
Moreirense possible starting lineup:
Kewin; Pinto, Santos, Marcelo, Frimpong; Franco, Ofori; Codisang, Alan, Camacho; Luis
Porto possible starting lineup:
Costa; Pepe, Marcano, Pepe, Sanusi; Otavio, Grujic, Eustaquio, Galeno; Navarro, Taremi