Ashley Young scored a late equaliser to rescue a point for Manchester United after Basel threatened a major shock at Old Trafford.
Danny Welbeck's double put United in control at half-time before the Swiss side stunned their hosts with a spectacular spell of three goals in 16 minutes after the break to leave Sir Alex Ferguson's side on the brink of their first home defeat in 17 months.
United's defending was shambolic throughout and Basel looked to have inflicted a serious blow on their Champions League campaign as Fabian Frei pulled one back before Alexander Frei headed the Swiss level, then gave them the lead with a penalty 14 minutes from time.
The shock to the system woke United from the slumbers - but it was only Young's last-minute header from Nani's cross that spared them only their third loss in 54 Champions League games at Old Trafford in the last decade.
Ferguson may clutch at the consolation of salvaging a draw but there was little else to satisfy United or their manager as they were run ragged by Basel's lively attackers.
Rio Ferdinand and Phil Jones suffered a torrid time in central defence as Basel striker Marco Streller terrorised the labouring England veteran and his young partner, who was given a rude awakening after winning plaudits for his performances in the Premier League.
Welbeck was selected ahead of Michael Owen and Dimitar Berbatov and he was one of the few United players to emerge with any credit on a night when a draw was arguably an exaggerated reward for dreadful performance.
While United were grateful to accept the opportunities offered by Basel's defence, they were fortunate not to be punished themselves as the Swiss created chances of their own from the start.
The first came after only four minutes when Streller played in Fabian Frei but he seemed to panic under pressure from Ferdinand and lashed his finish high and wide into the Stretford End.
It set the pattern for a slipshod performance at the back - but Welbeck's finishing provided relief as he scored twice inside 90 seconds to ensure they had a flattering two-goal lead at the interval.
Welbeck's first came after 16 minutes when he beat Basel keeper Yann Sommer with a scuffed finish after he was set up by Fabio and Ryan Giggs - and Giggs was involved again as Welbeck swiftly added his second, this time with a far more convincing strike from the veteran's cross.
Far from being discouraged, Basel continued to fashion opportunities only to let United off the hook. Alexander Frei was the culprit after being set up again by the dangerous Streller and Jacques Zoua shot tamely into the side netting from an angle with United exposed again.
If United thought they had escaped and half-time would interrupt Basel's momentum, they were given a rude awakening as the Swiss were level within 15 minutes of the restart.
Goalkeeper David De Gea, who had been blameless amid the mess of United's performance, blocked crucially from Streller - but the reprieve was brief as Basel's superb comeback started after 58 minutes.
De Gea made another fine stop from Streller's header but the rebound fell invitingly for Fabian Frei to score.
And two minutes later Basel were on terms as Fabian Frei delivered a perfect cross for his namesake Alexander to beat the keeper with a powerful header.
Ferguson's side had lacked rhythm and tempo even when they were ahead and now they were badly unsettled by Basel's continued ambition and ability to create chances with regularity.
And with Old Trafford silenced they took the lead from the penalty spot after 76 minutes. Jones hesitated with dire consequences, forcing Antonio Valencia to fell Streller. Alexander Frei stepped forward to send Basel's travelling fans into ecstasy by giving De Gea no chance.
Dimitar Berbatov was introduced for Anderson with nine minutes left, but it was another substitute Nani who played a part in a trademark Old Trafford grandstand finish that saw Young arrive at the far post to head past Sommer.