The Champions League is certainly living up to its billing of throwing out unpredictable results. In another day of upsets, Real Madrid, Arsenal, AC Milan and Manchester City suffered defeats as the Group stages turned on its head on Matchday Three.
Real were outplayed for much of the game by Borussia Dortmund, with the German side giving their home fans a dream 2-1 victory over the Spanish champions. City fell further adrift in the Group of Death, crashing to Ajax Amsterdam 3-1, as Roberto Mancini failed yet again to solve the European puzzle.
At the Emirates, Arsenal were equally poor, putting in a similar performance to the one at Norwich City at the weekend to deservedly lose 2-0 to Schalke - Klass-Jan Huntelaar and Ibrahim Afellay scoring the goals.
The Gunners began the better side, taking control in the first 10-15 minutes, but failing to find anything close to a clearcut chance - as the game wore on a half-chance was even hard to come by as the alarming lack of cutting edge came into view.
Schalke grew into the game in the second part of the first half, with Jefferson Farfan and Atsuto Uchida giving left-back Andre Santos a torrid time - the Brazilian will want to forget this game quite quickly if he is to carve any sort of career with Arsenal as a defender.
Steve Bould, in charge for Arsenal as Arsene Wenger endured his final game of a three-match touchline ban, should have brought on Laurent Koscielny and put Thomas Vermaelen at left-back as Schalke continued to bring wave after wave of attacks down their right.
Klaas-Jan Huntelaar missed a wonderful near post chance off a cross from Uchida, with Santos for the umpteenth time caught out of position.
The second half saw the Brazilian remain in the lineup, as Schalke continued to take a stranglehold of the game. A couple of sniffs for the Germans came and went with the decisive goal coming in the 76th minute. A little bit of head tennis was followed by Ibrahim Afellay heading the ball to Huntelaar, who was left all alone by the Arsenal defense, and the Dutch international made no mistake, dispatching the ball expertly past Vito Mannone.
Bould had brought on Olivier Giroud with 20 minutes to go, with Andrey Arshavin and Serge Gnabry - making his Champions League debut - coming on in the final ten minutes, although surprisingly Santos stayed on, with Carl Jenkinson instead strangely substituted.
Schalke sealed the game on the counterattack -- Santos again caught out as Farfan drilled in a low cross for Afellay to tap in with four minutes remaining, and hand Arsenal their first defeat to a non-English side in the Champions League since 2003.
Schalke took the lead in Group B, with seven points from three games, while Arsenal fell to second on six points. Olympiakos grabbed a 2-1 win at Montpellier to register their first points of the campaign.
At Westfalenstadion, it was all about the German champions as Robert Lewandowski opened the scoring for Dortmund off a mistake from Iker Casillas, which was quickly cancelled off by Cristiano Ronaldo in the 38th minute.
Dortmund got a deserved winner with just under 20 minutes to go, as Marcel Schmelzer netted to give his side all three points.
In Amsterdam, Ajax brought themselves right back in the group, with a commendable 3-1 victory over the English Premier League champions. Siem De Jong, Niklas Moisander and Christian Eriksen scored for the home side, after Samir Nasri had given City the lead in the 22nd minute.
Man City, with one point from three games, now lie five points adrift of second-placed Real Madrid, with Dortmund topping the group on seven points, as qualification to the knockout rounds looks increasingly difficult for the English side.
Results: Group A: Dinamo Zagreb 0-2 PSG; Porto 3-2 Dynamo Kyiv. Group B: Arsenal 0-2 Schalke; Montpellier 1-2 Olympiakos. Group C: Zenit 1-0 Anderlecht; Malaga 1-0 Milan. Group D: Dortmund 2-1 Real Madrid; Ajax 3-1 Man City.