The playmaker, twice AFC Player-of-the-Year, fired a left foot effort from the edge of the area in the 66th minute that took a heavy deflection off an onrushing defender to bounce past a wrong-footed Abbas Hassan in the Lebanon goal.
The final whistle brought huge cheers from the home fans in Tashkent, who have seen their side rebound brilliantly after taking only two points from their opening three Group A games.
Their third consecutive 1-0 victory leaves them on 11 points, one ahead of South Korea who beat Qatar 2-1 earlier on Tuesday, and crucially four ahead of third placed Iran. Korea and Iran have three games remaining.
The top two from the group qualify for the 2014 finals in Brazil while the third placed side faces two playoffs against another Asian country and then a South American team for another berth.
For Lebanon, their fourth defeat in six matches leaves their unlikely World Cup dream all but over after an eventful campaign where they have had to deal with a matchfixing crisis at home and shock player retirements.
They have four points from six games with a home tie against the Koreans and a trip to Iran remaining in June.
Theo Bucker's side looked dangerous on the break in the opening stages of the clash in Tashkent with Hassan Chaito going close with a left foot drive in the 12th minute.
But the home side always looked the most likely to grab the breakthrough and Djeparov was one of a number of Uzbeks guilty of wasting chances before the skipper came up with the key strike in the second half.
Uzbekistan are away to South Korea in their next qualifier in June before they finish their pool campaign against Qatar.
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- Abbas Hassan