Benitez under pressure ahead of Napoli's Champions League clash with Arsenal Rafael Benitez is facing his first rumblings of discontent at Napoli where defensive blunders and his habit of tinkering with the team have upset the supporters. Napoli need to beat Arsenal at home in their Champions League clash on Wednesday to reach the last 16 for the second time in a row and even then they will depend on Borussia Dortmund's result at Olympique Marseille. Arsenal need a draw to qualify for the round of 16 for the 14th season running and, having already won away to Borussia Dortmund in Group F, they are unlikely to be intimidated by the San Paolo stadium despite its fearsome reputation. If Napoli and Dortmund both win, they and Arsenal would all finish on 12 points, leaving the qualifiers to be decided on the results involving the three teams. This would in turn come down to goal difference, as all three sides would have nine points. Helped by the windfall they obtained from selling Edinson Cavani to Paris St Germain, Napoli were Serie A's biggest spenders in the close season as they splurged 37 million euros ($50.63 million) on Gonzalo Higuain alone. They started the season well with four league wins in a row but have now drifted eight points behind Serie A leaders Juventus. On Saturday, they threw away a two-goal lead in a 3-3 draw at home to Udinese which earned them a chorus of jeers from the home crowd, the first since Benitez replaced Walter Mazzarri as coach in the close season. "We have to do better in defence," said the former Chelsea, Liverpool and Inter Milan coach. We have committed individual mistakes that we cannot allow to happen. Everyone expected Napoli to be playing the way we were at the start of the championship and with more points in the bag. I'm as unhappy about it as anyone else. Against Arsenal, we have to score two or three goals and play better in defence. Benitez's own selection policy is also in the spotlight. He has fielded 14 different line-ups in Napoli's 15 Serie A matches so far and the mistakes on Saturday were made by players he brought in under his rotation system. Defender Federico Fernandez let Udinese back into the game with an embarrassing own goal seconds before halftime and second choice goalkeeper Rafael misjudged a Bruno Fernandes shot to allow Udinese to make it 2-2. Napoli's previous home game ended in a 1-0 defeat to mid-table Parma. Arsenal manager Arsene Wenger is baffled by the way the group has turned out, with Marseille losing all their matches and the other teams taking points off each other. "It's the first time I've seen that (12 points is not enough) after 150 Champions League games," he said after his team beat Marseille in their last match. It's unbelievable but it's reality. It's tricky but we have to finish the job. I will have to play a full-strength team against Napoli. I can't take any risks. "It would be a mistake to think we just don't have to lose big," added Wenger. We have to play in a positive way and try to win the game, anything else will be a gamble.