Russia dominated the match throughout and led comfortably through Everton midfielder Diniyar Bilyaletdinov's brace. However, substitute Nejc Pecnik's header two minutes from time left the tie in the balance at 2-1, and they could even have levelled as Marko Suler forced a superb stoppage-time save from Igor Akinfeev.
"The match left me with mixed feelings," Semak told RIA Novosti. "On the one hand, I'm pleased we won, but on the other hand, the way the game ended doesn't leave you at ease in the run-up for the next match."
Slovenia produced little in attack and Robert Koren's 88th-minute shot in the build-up to Pecnik's goal was their first on target. Semak added: "They didn't surprise us because it was obvious that they came here with the aim of not allowing a goal. Only after we scored the second goal did they go all out."
Goalscorer Bilyaletdinov opted to let his football do the talking, offering only the assertion that: "All commentaries will be after the second match."
Slovenia coach Matjaz Kek was relieved after Pecnik's contribution, and told the Slovenian FA's official website, nzs.si: "We have found a goal that keeps us in the game. In the first half we gave away a stupid goal, and we also started badly in the second half when (keeper Samir) Handanovic kept out some dangerous moves from the Russian team."
Kek is hopeful for Wednesday's clash in front of his nation's own fans, and continued: "The People's Stadium can create a positive outcome. We must recover and prepare for the return meeting."