Scotland's Euro 2020 qualification hopes are fading after Stephen O'Donnell's own goal condemned it to a 2-1 home defeat to Russia.
Guilherme's goalkeeping calamity handed John McGinn his first international goal 10 minutes in, but Scotland failed to build on its strong start.
With Artem Dzyuba drilling in an equaliser five minutes before half-time, Russia – through the exceptional Aleksandr Golovin – took control after the interval.
Their dominance was rewarded when Yuri Zhirkov's attempted tap-in squirmed in off O'Donnell.
The woodwork twice denied Russia a third to give Scotland hope, but the visitor held firm to secure a victory which takes it six points clear of Steve Clarke's side in Group I.
Guilherme made an instinctive stop to keep out O'Donnell's ninth-minute effort, but he was soon at fault for Scotland's opener when he spilled Ryan Fraser's cross straight to McGinn.
David Marshall preserved Scotland's lead soon after, reacting sharply to tip Dzyuba's header over, though he could do nothing to deny Russia's captain in the 40th minute.
Having latched on to Golovin's cut-back, Dzyuba made no mistake with a firm finish.
Charlie Mulgrew's block from Golovin's strike maintained parity shortly after the restart, before the Russia playmaker sliced wide from the edge of the area.
Golovin was causing havoc, though, and he turned provider once more when he raced behind Scotland's lines and drilled in a low cross which O'Donnell bundled into his own net.
Marshall tipped Mario Fernandes' header onto the crossbar as Russia aimed to wrap up the win.
The post then came to Scotland's rescue from Magomed Ozdoev's effort, and Russia spurned further chances, but the home side could not make its good fortune count.
What does it mean? Scotland's chances look slim
With six points from its opening five qualifiers, and Belgium up next, Scotland's hopes of automatic qualification are hanging by a thread.
A play-off spot is now likely the primary aim for Clarke, who must ensure his side – which faces Russia again in October – makes sure of maximum points when it comes to its final three Group I games against San Marino, Cyprus and Kazakhstan.
Golovin rediscovers World Cup form
Russia's Golovin was a standout performer at the 2018 World Cup but has struggled to recapture the levels of those performances since moving to Monaco on the back of that tournament. However, he proved his quality with an all-action display on Friday, setting up both of Russia's goals from his role behind Dzyuba.
Guilherme caught out
Brazilian-born Guilherme has been Russia's first-choice goalkeeper since Igor Akinfeev retired, though he looked unaccustomed to the international stage throughout Friday's encounter, no more so than when he gifted McGinn the opener.
Scotland faces Group I leader Belgium at Hampden Park on Monday, while Russia hosts Kazakhstan.
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