Lithuania stun Czech Republic
Striker Milan Baros had a penalty saved as the Czechs made a disappointing start to their qualifying campaign following on from their failure to qualify for this year's World Cup finals.
The hosts dominated for long periods but an unmarked Sernas grabbed the only goal when he headed past keeper Petr Cech in the 26th minute.
"Mainly in the final phase we achieved very little, that is just sad," said Czech skipper Tomas Rosicky.
"In such a match, you have to create even more chances. We made the qualification difficult for ourselves right from the start."
Baros missed a chance to equalise from the penalty spot five minutes before half-time, keeper Zydrunas Karcemarskas parrying his strike.
The Czechs next face Scotland on October 8 while Lithuania, who have four points from two matches, travel to world champions Spain.