'The Amazing Race 21' Episode 8 preview: Abbie and Ryan's troubles continue in Russia [Exclusive video]

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How the mighty have fallen. After a missed connection in Frankfurt set them half a day behind four of the final six teams competing in "The Amazing Race" last week, divorced daters Abbie and Ryan trudged through the roadblocks and detours of Moscow like a dead team walking. Their odds of surviving to the next leg increased, unbeknownst to them, when a taxi driver drove off with rockers James and Abba's bags and Abba's passport.

Judging from this exclusive clip, the couple lived to see another red dawn. But don't break out the vodka and caviar just yet, as Ryan is sent back to school where his time-telling skills are literally tested. His put-upon girlfriend starts off positive as round one begins with the map of the Russian Federation's time zones looming ominously overhead. "He's really good with memorization and has a system down, so it's just a matter of him being able to get it in the amount of time." The cocksure Ryan speeds through, jumps up, and declares (while gathering his belongings), "Done. Got it. Nailed. You have my clue?"

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Abbie, huddled in the corner, already looks worried by his bravado, and it turns out she should be, as the cross between a professor and a James Bond villain grading the exam declares his quiz incorrect. Ryan, per usual, is so sure of himself that he is in denial. "No way. That was right. There's no way those are wrong." As he plows through at least eight other rounds, growing increasingly deflated and irritated, even ripping one test to shreds before turning it in for grading, Abbie tries to calm down her impulsive teammate: "Relax. Deep breath."

Tune in Sunday at 8 PM on CBS to see if Ryan eventually graduates before straggling Professor Spectacles, if Abba recovers his passport, and who will be the next team eliminated from "The Amazing Race."