Portsmouth 0 Arsenal 1: Arsenal, with all their feints and reverse passes, are masters of the unexpected, but they surprised even themselves yesterday. The game was won by a man without a Premiership goal to his name for 16 months, and Sol Campbell can hardly have anticipated ending the dearth here, let alone doing so with a 30-yarder.

The visitors are often and properly scolded for an inability to come up with an alternative on occasions like this when their passing style leads nowhere. It is most improbable that Campbell can go on being a one-man plan B, but in the 76th minute he did deliver the kind of unmerited, victory that nurses hope.

Arsenal's morale may still be sickly given this wan display, but they could savour a feeling of relief. They move into second place and keep themselves within five points of leaders Chelsea, but they had to stay in touch on a day when the opposition disputed every square yard.

Portsmouth, indeed, did more than that. While Arsenal's intentions were elegant they seldom came to fruition, but Joe Jordan's side were relentless in their labour and sharp enough to create clearer chances. Nonetheless, the champions won for just the third time in nine league games.

In public at least they will not be excoriating themselves. Warmth was barely returned to frozen bodies when Arsene Wenger was already reinterpreting the afternoon. "It was a performance with a lot of spirit," he said. "We needed to be solid defensively and wait for our goal. We did it well."

Spoken like a manager determined to protect whatever faith remains in Arsenal souls. "We feel we are in the race. It's down to how well we do game by game," said Wenger, who fended off Jose Mourinho's suggestion that Chelsea, in their present form, are all but irresistible. "There's a long way to go and things can change quickly over Christmas."

During this congested period, Arsenal will have to do without Jose Antonio Reyes. His ankle injury ruled him out here and a 10-day recovery period would prevent him from facing Fulham or Newcastle. Yesterday Portsmouth made a vastly committed effort to deepen any sense Arsenal have of being beleaguered.

Robert Pires, howled at by a Fratton Park crowd still irate over his dive for a penalty at Highbury last season, looked as if he wished he was elsewhere and made so small a contribution that he might have been entirely absent. Others, too, were faint presences and, astonishingly, Patrick Vieira came into that category.

Returning from suspension, he seemed bemused by the physicality and he was barged aside on several occasions. The busy and skilful Steve Stone dealt with Vieira in that fashion twice within a few moments, sending Yakubu Aiyegbeni away on the second occasion in the 64th minute, only for the forward to make nothing of the opportunity.

Stone had also released Gary O'Neil 10 minutes before the interval, and though the young midfielder did well to avoid Kolo Toure's attempted recovery he eventually pulled the ball wide.

Portsmouth, springing Lomana LuaLua from the right wing to aid Ricardo Fuller, always carried a threat while still retaining the numbers to crowd out Arsenal.

Jordan agreed that the inability to take chances had prevented Portsmouth from executing their plan perfectly. Fuller, in particular, was slightly short of precision or composure. He dithered over some openings and had a drive deflected wide when LuaLua set him up after 44 minutes.

Portsmouth had enough conviction to pursue an equaliser and, with nine minutes left, a Stone attempt reared up from the turf to hit Manuel Almunia at chin height. Almunia responded well to deal with LuaLua's attempt from the rebound, even if he was denied some credit by an offside decision.

Arsenal, as Wenger agreed, had been creative only before the interval. One move ended with Thierry Henry unable to beat the goalkeeper, Jamie Ashdown, who had been quick to reach him, and another saw Robin van Persie, starting in the Premiership for the first time, fire negligently high.

Wenger himself did not dispute the assertion that Campbell had been the least likely member of the team to finish beautifully. But with 14 minutes left he took a pass from Vieira, strode forward and thrashed a long-range drive past Ashdown at his near post.

The centre-half did have a small piece of good fortune. Jordan explained later that Aiyegbeni might have been tracking Campbell had he not just suffered a knock. The Arsenal defender may have been just as important in ensuring that his side did not concede from a set-piece this time.

Arsenal never conveyed the impression of a watertight team, but an uncommon clean sheet will be a starting point as they search for their old assurance.

Portsmouth will let few others take any encouragement from Fratton. Jordan again said he was happy with his position as coach to Velimir Zajec's executive director. This was the first defeat for them in five Premiership games and the chairman, Milan Mandaric, must consider preserving their partnership, with only the job titles to be adjusted.