Champions League holders Real Madrid slumped to a surprise defeat in the competition as they went down 1-0 away to CSKA Moscow on Tuesday.
Real were not expected to struggle in group G as they look to continue their recent dominance of Europe’s elite competition, but Julen Lopetegui’s side went behind inside two minutes in Moscow following a mistake by Toni Kroos.
The German’s drilled backpass turned into a gift for Nikola Vlasic, and the winger on loan from Everton fired past Keylor Navas to put CSKA ahead.
Casemiro hit the post in the first half – one of three attempts that found the woodwork for the visitors – but Real, without Gareth Bale and Sergio Ramos, failed to make their possession count as CSKA held on to move top of group G.
Los Blancos will nevertheless expect to bounce back next matchday against Czech champions Viktoria Plzen, who were crushed 5-0 by Roma, with striker Edin Dzeko netting a hat-trick.
At Old Trafford, the pressure continued to build on Mourinho as United produced another insipid attacking display in their goalless stalemate with Valencia.
They are now four games without a win, as Mourinho’s decision to recall Alexis Sanchez – after dropping the Chilean for the weekend defeat at West Ham United – failed to pay off.
Earlier, Juve continue to lead the group after easing to victory against 10-man Young Boys in Turin, with Dybala scoring a hat-trick to take centre stage in the absence of Cristiano Ronaldo, who was serving a one-game ban.
Pep Guardiola saw Manchester City come from behind to beat Hoffenheim in Germany in group F.
City next face Shakhtar Donetsk, who squandered a two-goal lead to draw 2-2 with Lyon in France, in a game played behind closed doors.
Meanwhile, stuttering Bayern could not hang on to the early lead given to them against Ajax when Mats Hummels headed in Arjen Robben’s cross. Young full-back Noussair Mazraoui equalised to give the Dutch side a 1-1 draw.
Those sides are level atop group E ahead of Benfica, who won 3-2 in a thriller at AEK Athens with Alfa Semedo scoring the deciding goal.