Witsel: Our chances are good against Liverpool
Last week Brazilian striker Hulk and verteran midfielder Sergei Semak struck in the space of three second half minutes to leave Liverpool with a mountain to climb at Anfield in the return leg.
Witsel said: "Liverpool are a very good team but we were the better side last Thursday. We clinched a two-goal advantage keeping our net clean in the first match. Our chances in the return leg look good as Liverpool need to score three goals to advance."
The 24-year-old Belgian international added: "Of course Liverpool will try to turn the situation in their favour and I expect a very tough match. But we are also preparing for this clash seriously and I believe we can resist their pressure."
With the Russian League still in its winter hibernation and not due to resume until 9 March Zenit's win over Liverpool was their first official match of the 2013.
They are seeking their second taste of European glory after beating fallen Scottish giants Rangers for the then UEFA Cup title in 2008.