Ralf Fahrmann's fine display was not enough to earn Schalke a win as Otavio's penalty helped Porto claim a 1-1 draw in their Champions League Group D fixture.
Iker Casillas became the first player to feature in a 20th Champions League campaign, but it was Fahrmann who left his mark at Veltins-Arena with a string of superb saves.
Having brilliantly kept out Alex Telles' spot-kick, Fahrmann somehow denied Felipe from point-blank range early in the second half before Breel Embolo nudged Schalke ahead just after the hour.
Fahrmann could not repeat his earlier heroics in the 75th minute, though, as Otavio stepped up to convert from the spot and secure a share of the spoils after Naldo had clumsily brought down Moussa Marega.
With all eyes on Casillas, it was Fahrmann who took the limelight in the 13th minute, getting down low to tip Telles' shot wide after referee Jesus Gil Manzano deemed Naldo had deliberately handled in the area.
Naldo could have made amends at the other end soon after but, having met Daniel Caligiuri's free-kick, the veteran defender failed to keep his header down.
Fahrmann was at his best again two minutes into the second half, reacting instinctively to prevent Felipe bundling in from three yards out.
Casillas could not replicate Fahrmann's form at the other end in the 64th minute - Embolo slotting home through the 37-year-old's legs after latching onto Weston McKennie's cross.
Schalke’s lead was short-lived, however, as - following a rash challenge on Marega by Naldo - Otavio sent Fahrmann the wrong way from 12 yards.
Yevhen Konoplyanka had the chance to snatch the points in the closing stages, only for the Ukraine international to drill wide from close range as Porto held firm.
What does it mean: Schalke show their grit
It has been a dreadful start to the Bundesliga season for Domenico Tedesco's side, who have lost their opening three games, but they displayed their resilience on Tuesday against a Porto side packed with attacking talent, and would have had the points if not for Naldo's clumsiness.
Pat on the back: Fahrmann steals Casillas' thunder
Despite Casillas' landmark appearance making headlines prior to kick-off, Schalke's Fahrmann proved his quality with a string of superb stops. The German has conceded six goals in three Bundesliga fixtures so far, but today's performance will go some way to restoring his confidence.
Boot up the backside: Naldo blunders prove costly
Schalke may feel aggrieved at the referee’s penalty decisions, but Naldo only has himself to blame for a ludicrous decision to dive in on Marega, who made the most of the contact, and Fahrmann was not able to spare the defender's blushes for a second time.
It is a return to Bundesliga action for Schalke, who have the small task of hosting Bayern Munich. Porto, meanwhile, travel to Vitoria Setubal in their next outing.
|Foles fuels Eagles´ upset win over Rams|
|Latham carries bat as New Zealand leave Sri Lanka reeling|
|Keep your cool, Virat – Paine and Kohli in another confrontation|
|Depleted Nuggets complete season sweep of Raptors|
|Fabinho was ´outstanding´, says Klopp|
|Patriots QB Brady on loss to Steelers: We aren´t playing well enough to win|
|Elliott says Cowboys´ shut-out loss to Colts was embarrassing|
|De Bruyne not worried about Liverpool title challenge|
|Sixers star Simmons makes history with triple-double|
|WATCH: Nowitzki receives standing ovation in first home game of season|
|Seattle´s playoff spot on hold after Seahawks suffer OT loss to 49ers|
|Cheika survives as Wallabies coach, Johnson appointed|
|Vikings remain in NFC playoff picture|
|Steelers stay ahead as Patriots lose AFC´s second seed|
|Lionel Messi is the best, says Amor|
|I´m still tired just looking at Robertson – Mourinho in awe of Liverpool intensity|
|Casillas takes swipe at Mourinho after United lose to Liverpool|
|Valverde relieved as Messi brilliance prevents another Levante nightmare|
|WATCH: Leno proposes to girlfriend after Bears clinch division title|
|Messi and Suarez the world´s best strike partnership, says Pique|
|Klopp: I cannot keep every Liverpool player happy|
|Messi and Suarez outscoring Real Madrid and Atletico in LaLiga|
|Levante 0 Barcelona 5: Marvellous Messi banishes ghosts of last season|
|Colts rout Cowboys to keep playoff hopes alive|
|Bears shake off Packers to win NFC North and return to playoffs|
|Mourinho explains Pogba omission and defends Lukaku´s Liverpool showing|
|Liverpool´s display against Manchester United one of the best, claims Klopp|
|Look away Jose! Damning stats expose Manchester United´s limp Liverpool loss|
|Time´s up, Mourinho: Manchester United can dither no longer|
|Manchester United´s players are not dishonest – Mourinho|
|Manchester United´s lack of ambition under Mourinho is scary – Keane|
|Mourinho: All Manchester United can achieve is fourth|
|Quagliarella should be protected by UNESCO, jokes Sampdoria coach|
|Manchester United surpass last season´s goals-against tally in first 17 games|
|Hasenhuttl revels in ´unbelievable´ victory over Arsenal|
|Liverpool 3 Manchester United 1: Shaqiri´s late show bails out Alisson as Reds return to the top|
|Edinburgh in control in Champions Cup, Racing win again|
|Emery ponders January signing after Bellerin injury|
|It is only a knock – Sarri plays down Hazard injury fears|
|Redskins QB Alex Smith released from hospital|
|Starc: If I listen to Warne, I may as well retire|
|Curry interviews retired NASA astronaut, apologises for moon comments|
|Hazard refusing to give up on Premier League title hopes|
|Ziyech & Blind score hat-tricks as Ajax claim 8-0 win|
|Canelo v Fielding: What next for three-weight champion Alvarez?|
|Southampton 3 Arsenal 2: Austin and Ings end Gunners´ long unbeaten run|
|Brighton and Hove Albion 1 Chelsea 2: Sensational Hazard proves the difference|
|Pogba on the bench as Clyne starts for Liverpool|
|Lipsky ends long barren spell in Malelane|
|Lakers´ Stephenson to repeat air guitar despite technical|
|Fletcher pushed Miller on to Broncos sack record|
|The Sarri effect: Hazard surpasses 2017-18 goal involvements in just 16 games|
|Van der Burgh retires on a high note with breaststroke double|
|Rashford: Liverpool was never an option|
|No team Liverpool play this season will be as motivated as Man United – Klopp|
|India surprised by contentious Kohli decision - Bumrah|
|The Sunday Seven - 7 Key Opta facts for NFL Week 15|
|Miller eyeing Joshua bout at Madison Square Garden|
|Finch cleared of serious damage after another finger blow|
|Rashford ´untouchable´ because he plays on his limits – Mourinho|
|It´s important to have his mentality - Mayfield thrilled with Kobe Bryant visit as Browns beat Bronc|
|Centurion Latham indebted to ´world-class´ Williamson|
|Spurs´ Dier out until January after appendix removal|
|A-League Review: Glory down Jets to stay unbeaten|
|Philander ruled out of first Test|
|Controversial Kohli dismissal puts Australia in command|
|Thunder´s Westbrook: ´When we defend like that — best team in the league´|
|Kante at his best further forward, reiterates Sarri|
|Rose capitulates in Indonesia to squander chance to top rankings|
|Fielding: The better man won but I lived a dream|