Russia's hopes of rebuilding in time for the 2018 World Cup suffered another blow on Sunday as repeated defensive lapses allowed Costa Rica to claim a 4-3 friendly win.
With coach Stanislav Cherchesov giving opportunities to young players, it was veteran defender Vasily Berezutsky who was the weak link.
The centre-back was distracted for Costa Rica's first goal, scored an own goal and gave away the penalty from which Joel Campbell scored Costa Rica's 92nd-minute winner.
With Russia 3-1 down at half-time, a planned ceremony to mark Berezutsky's 100th Russia game was called off, but after the break striker Artyom Dzyuba led a revival with two goals, before Campbell gave the visitors the win.
It was Cherchesov's first Russia defeat after an earlier draw with Turkey and win over Ghana.