Even before the protests started, the opinion polls had him behind Klitchko or Yatsenuyk in head to head elections by 15-10 points Ahh but that's not how Ukraine's presidential elections work and there is no indication the opposition would unite behind a single leader other than Yulia Tymashenko. This is why the European socialists were so insistant that she be released from prison as a pre-condition to their offer of associate status in their EU.
In a three way race Yanokovitch beats the two major opposition puppets much like Clinton did in 1992 with less than 50% of the vote.
The debate that the opposition leaders had was whether they should go separately for the
first round of elections. Whichever opposition leader got the most votes in the first round was to be the candidate going head to head against Yanukovich in the second round. There was no debate whatsoever that in the second round Yanukovich was to face one opposition candidate. This scenario was advocated by Tymoshenko, arguing that if Yanukovich was to campaign against all three of them, his efforts would be diluted (ie. not putting all your eggs in one basket) It also holds democratic appeal, since the one opposition leader is chosen by the voters in the first round, not in some back room agreement between the three leaders.
Those who wanted to see one candidate in the first round argued that this would show that the opposition is united and presents one concentrated common front against Yanukovich. If they a win by majority in the first round, second round wouldn't be needed.
For Yanukovich to beat the three leaders in the first round, he would need to get 50% +1 outright and the likelihood of that is nil