Napoli coach Walter Mazzarri is fearful of a Chelsea backlash in the first leg of its Champions League last-16 match on Tuesday.

Chelsea heads into the game in Naples licking its wounds after dropping to fifth in the Premier League and only managing a 1-1 draw in the FA Cup on Saturday against second-tier Birmingham City.

"Chelsea is worse than us at the moment but I don't trust (form tables),'' Mazzarri said. "We're maybe coming into the game better as a whole, but their team is one of champions, who are all used to the atmosphere of great international events. I'm sure that they will regroup for the occasion.''

In fact, the Italian sees the potential for a Chelsea fightback, starting at the Stadio San Paolo.

"Paradoxically, their difficulties at the moment in English competitions could be an extra obstacle for us. Even when results weren't happening for us we never stopped playing well, but single episodes made everything go badly.''

Chelsea coach Andre Villas-Boas acknowledged this week that he had lost the support of some players, but striker Didier Drogba insists they are all united in a bid to get the season back on track.

"I think we all are responsible for the results,'' Drogba said. "I think we all have to play our game, tomorrow is our chance. The good thing in football is that there is always another game to change bad, difficult moments. Tomorrow is one of those, we have to go out and enjoy the game.

"We feel that no one really believes in us. Tomorrow we are going to show we deserve to be here. It's a top game and we are going to have to get a good result. We have to be clever and do what the manager is going to ask us to do. Like always, of course. The best way is to believe we can do it. When you look at the squad, we have talent, we have goal-scorers here.''

Reports emerged that Drogba gave a halftime team talk during the Birmingham match to help inspire Chelsea's second-half comeback, but the Ivory Coast striker said it was merely the senior players displaying leadership.

"The manager made the speech at halftime.'' Drogba said. "He has leaders in the squad and we are here to help him. We wanted to gee the team up at halftime and nothing more. People are making a big thing about nothing.''

Napoli is full of confidence after rising to sixth in the Serie A standings with two successive victories. Edinson Cavani struck twice in an impressive 3-0 win at Fiorentina on Friday to take his tally for the season to 15 in the league.

In contrast to Champions League newcomers Napoli, Chelsea has a strong pedigree among Europe's elite, with four semifinal appearances and a losing final in 2008.

However, Mazzarri's men have already dumped one Premier League team out the competition and, despite the coach's word of warning, his players will be quietly confident they can do the same to Chelsea as they did to Manchester City in the group stage.

Chelsea owner Roman Abramovich has been ruthless in the past and brought in Villas-Boas to replace Carlo Ancelotti, who was fired in the offseason only a year after leading the club to its first Premier League and FA Cup double.

Since Jose Mourinho left in 2007, Abramovich has employed five managers but Villas-Boas claims he doesn't fear for the ax.

"From messages you have received recently from the club it is clear there is a change on the way,'' Villas-Boas said. "There is a great belief in what we are working towards for next year, although that doesn't change the responsibility we have this year.

"It's normal, looking at the results that we've had and the way things were done in the past, that there is this speculation. There is full belief from the owner in what we're doing.''

Villas-Boas is also confident that whatever happens Tuesday, Chelsea will emerge triumphant after the return leg in two weeks.

"It's a first leg, so tomorrow will not be decisive yet,'' he said. "Stamford Bridge is a great stadium for Euro nights and that's why we really wanted to win the group, so we could have the opportunity to turn things around or continue on positive route.''

Chelsea captain John Terry faces a late fitness test Monday but is a "major doubt.'' Villas-Boas is more confident Ashley Cole will be given the green light to play following injury.

Napoli defender Hugo Campagnaro is set to miss out with a calf injury, and will again be replaced by Gianluca Grava.

Mazzarri will be forced to watch both legs from the stands as punishment for his altercation with Villarreal striker Nilmar in the group match in December.

All eyes will also be on matters off the pitch. Fans from Manchester City, Liverpool and Bayern Munich have all suffered violence, including stab wounds, on recent visits to the Italian city.

Napoli has issued a public plea to its fans to behave.

"Napoli makes a further and even stronger appeal to fans to respect the current norms in security matters, in line with UEFA rules,'' a club statement read. "Norms that if violated would provoke a stadium ban and hence compromise other big international events here.''

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