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.
|Second-half blitz guides Leicester to European success|
|Sheffield Wednesday 1 Middlesbrough 2: Besic, Assombalonga see off Owls|
|Goerges rallies to reach Luxembourg Open final, Jabeur makes history|
|Howe: Transfer speculation will not disrupt Ake|
|´Do we really want opera every night?´ - Klopp not changing Nations League view|
|Vile and abhorrent – Chelsea´s Carney responds to online abuse|
|Giants WR Beckham Jr. explains why he might cramp up: ´I really don´t like water´|
|Man City pay training-pitch tribute to Joe Hart|
|Neymar to be rested as Tuchel rubbishes Ballon d´Or concerns|
|Sarri ´not interested´ in Christensen father´s quit threat|
|Cardinals fire offensive coordinator McCoy after 1-6 start|
|Neymar return unlikely, but anything can happen – Valverde|
|Bairstow a doubt for fourth ODI|
|Manchester United fined for late arrival and delayed kick-off against Valencia|
|Australia-Pakistan chat not ´especially polite´ - Sarfraz|
|Pogba relishing ´pressure game´ against in-form Hazard|
|Don´t bet on Cardiff survival, warns Warnock|
|Buffon enjoying Tuchel´s methods at PSG|
|RIP to Wimbledon epics! Isner feels like The Undertaker following final-set tie-break rule|
|Sevilla performance sealed Bernat´s Bayern exit - Hoeness|
|Keita set to miss out as Liverpool monitor injured stars|
|He didn´t want to be here – Guardiola doubts Sancho will return to Manchester City|
|Sarri: Manchester United are the best in the Premier League|
|Mourinho salutes ´brave´ Shaw for ´best possible´ response to criticism|
|No Ballon d´Or distractions for Griezmann, insists Simeone|
|Wigan stand by Hardaker as full-back prepares to undergo rehabilitation|
|Barcelona deny Neymar talk|
|Hazard can win the Ballon d´Or as a Chelsea player, insists Sarri|
|De Bruyne in contention to start in Manchester City´s clash with Burnley|
|Neymar needs to mature to reach Messi levels - Xavi|
|We have a hell of a lot to do - Paine slams Australia batting|
|Kerber and Osaka to meet at WTA Finals|
|Lorenzo out of Japanese MotoGP|
|Real Madrid handed Africa trip in Copa del Rey|
|Allegri: Ronaldo has sharpened Juventus focus|
|No Wade in Wasps squad amid NFL reports|
|Rooney: Five of us controlled Man United dressing room|
|Bayern bosses launch scathing attack on ´disrespectful´ media|
|Saints lock in Lawes to new deal|
|Adelaide United 1 Sydney 1: Debutant Le Fondre rescues a point|
|Madrid can´t look back, only forward - Lopetegui confident of revival|
|Wimbledon to introduce final-set tie-breaks|
|Abbas inspires Pakistan to series victory|
|Madrid boss Lopetegui hopeful on Bale availability|
|Mood is positive at Bayern, insists under-pressure Kovac|
|LeBron offers food for thought after losing Lakers debut|
|Bolt future not an immediate concern for Mariners|
|Hazard: I could finish my career at Chelsea|
|Buffon hoping to avoid Champions League final against Juventus|
|Wilshere not ready for West Ham return|
|Chelsea v Manchester United: Hazard better under Sarri than he ever was with Mourinho|
|The big Friday Premier League quiz|
|Khawaja suffers meniscal tear, doubt for India series|
|Babbel: Klopp must win trophies now at Liverpool|
|LeBron makes spectacular start on Lakers debut, but LA fall to Trail Blazers|
|Broncos thrash Cardinals to end losing streak|
|Price leads Red Sox past Astros and into World Series|
|LeBron makes fast start on Lakers debut with two massive dunks|
|Real Salt Lake 4 New England Revolution 1: Hosts boost play-off chances|
|Simmons gets triple-double in win over Bulls|
|´Ambitious´ Maguire wants Champions League football|
|Henry praises ´charismatic leader´ Falcao|
|WATCH: Cardinals WR Fitzgerald tackles former QB Warner on sidelines|
|Spurs right not to make signings – Pochettino|
|Icardi happy at Inter, close to contract renewal|
|This Week in U.S. Sports: Bosa leaves Ohio State while the World Series is almost set|
|Liverpool boost as Salah and Van Dijk join training|
|Cowboys discuss road woes, Prescott says team ´addressed the elephant in the room´|
|Isner scrapes through in Stockholm, Monfils eliminates Tsonga|
|Hinch says Altuve would be out with injury in regular season|