Roy Hodgson has made a frank admission that Liverpool could be vulnerable to a bid from Manchester United for Fernando Torres in January. The Liverpool manager also revealed he was caught unawares by Christian Purslow's departure as managing director only five days after overseeing the sale of the club to New England Sports Ventures.

Torres, out of form and out of Liverpool's squad to face Napoli tomorrow night, has looked a disillusioned figure at Anfield this season but has been touted as a potential replacement for Wayne Rooney should United sell him in the next transfer window. Sir Alex Ferguson has often dismissed the prospect of bringing a Liverpool star to Old Trafford as "unthinkable", while the last player to move directly between the two fierce rivals was Phil Chisnall in 1964. Rafael Benítez, Hodgson's predecessor as manager, insisted he would resign if Torres had been sold on his watch.

The present Liverpool manager, however, believes a United move for Torres cannot be discounted. "When a great player like Wayne Rooney is looking to leave his club, Manchester United will be in a position to target a lot of players around the world," Hodgson said. "I don't think Fernando Torres will be the only striker they target, and I don't think that we will be the only club that will be worried their striker can be targeted.

"I am not naive to believe there won't be any danger and we will never lose a player like Torres, I understand these things can happen. I don't believe we will lose him, we will do our best to ensure he stays, and I only hope I can do everything in my power to help him return to the very top level we know he has. I certainly hope he will get back very quickly, we want to get him back to form and back to the level we know he can achieve as quickly as possible."

One confirmed departure from Liverpool was that of Purslow, who was instrumental in the recent takeover drama and the appointment of Hodgson as manager in the summer. Purslow will continue at Anfield as a nonexecutive director and special adviser to the new owners but his exit as managing director, and its timing, came as a surprise. With the chairman, Martin Broughton, now in a transitional role while the Americans formalise a new board, it means four of the men who ratified Hodgson's appointment – Purslow, Broughton, Tom Hicks and George Gillett – have gone.

"Christian Purslow leaving doesn't impact on my position as far as I know, but that is not a question for me to answer," Hodgson said. "I came to work for Liverpool Football Club not an individual. I had no idea before today that Christian was going to leave the club. I believe I have the backing of the club, and I want to continue with the rebuilding job that we have here. We knew it was a big job, and as far as I am concerned nothing has changed."

Purslow, blamed by Benítez for Liverpool's recent woes only 24 hours before his departure, said he was looking forward "to assisting the owners in any way I can at this exciting time as they drive the club forward to a bright future".

Excitement and optimism do not describe the mood around Hodgson's team, however. It said everything about the paucity of the squad the Liverpool manager selected for this tie that, on their flight to Naples this morning, the most famous person on board was the pilot. Captain Paul Bruce Dickinson, whose numerous guises include being the lead singer of Iron Maiden, lent a celebrity touch to a journey minus three first-team players through injury – Dirk Kuyt, Glen Johnson and Daniel Agger – plus four more omitted by choice. Cue several shameless Maiden references from here on in.

Hodgson, a man on the edge, may have every justification in sparing Steven Gerrard, Torres, Raul Meireles and Lucas from Europa League duties ahead of Sunday's Premier League visit of Blackburn Rovers. A "must-win" game, the former Rovers manager admitted following Everton's convincing victory at Goodison Park.

For a manager yet to develop any continuity or understanding in his new team, whom the vast majority of supporters wish he would run to the hills and whose last gamble imploded against Northampton Town in the Carling Cup, his selection threatens to play with madness at the Stadio San Paolo.

"It was a very straightforward decision for me because it's a question of priority," Hodgson said. "We have four points from two games in this group. We've started well. We've got four matches left to get the six points or so we need to qualify. For me it's quite simply a priority after our very, very poor start to the season and our bad results. If you've got to make a sacrifice with the team on one game then I'd make the sacrifice in this game. I agree we need to win but we badly need to win on Sunday. If we lose tomorrow night and people say I prioritised for Sunday, I will hold my hand up and say yes I did."

Probable teams: Napoli (3-4-2-1): De Sanctis; Grava, Cannavaro, Aronica; Maggio, Pazienza, Gargano, Dossena; Hamsik, Lavezzi; Cavani. Subs from Gianello, Vitale, Santacroce, Zuniga, Cribari, Yebda, Sosa, Blasi, Dumitru, Lucarelli.

Liverpool (4-2-3-1): Reina; Kelly, Carragher, Kyrgiakos, Konchesky; Spearing, Poulsen; Rodríguez, Cole, Babel; Ngog. Subs from Jones, Aurélio, Skrtel, Wilson, Darby, Pacheco, Shelvey, Eccleston, Jovanovic.

Referee T Kinhofer (Germany).