Tottenham Hotspur produced a sterling fight back coming from two goals down against FC Basel to give their hopes of winning their first European trophy in 30 years a much needed lifeline at White Hart Lane but injury to Gareth Bale has left their season hanging by a thread.
Valentin Stocker and Fabian Frei's goals gave the Swiss league leaders a deserved lead, before Emmanuel Adebayor's poked effort halved the deficit before the break.
Substitute Gylfi Sigurdsson lashed home an equaliser before the hour mark but Spurs will consider themselves fortunate not to have conceded a third as Mohamed Salah and Jacques Zoua both wasted chances to win it.
But despite their European hopes looking desperate, with a win or a high scoring draw required in the return leg in Switzerland in a week's time if they're to reach the last four for the first time in 29 years, the main focus will be on the injury to Bale, who left the pitch on a stretcher in stoppage time.
Seeking to put one foot in their first European semi-final since 1984, Andre Villas-Boas was force to name Adebayor in attack ahead of the injured Jermain Defoe while Kyle Walker was omitted from the squad, with Kyle Naughton filling in at full-back.
The unfancied Swiss league leaders had knocked out Manchester United in last season's Champions League and boasted Marco Streller in attack, scorer of 13 domestic goals this season.
And it was the 31 year old who posed the greatest threat in the opening minutes, first setting up Fabian Schar whose effort was beaten away by Brad Friedel before Streller himself tested the Spurs stopper after Valentin Stocker had ghosted in behind Naughton.
The hosts were finding creating similarly presentable opportunities a much tougher ask, with Bale's swept shot the best Spurs chance in a lackluster opening quarter.
The first half injury to Aaron Lennon defined Tottenham's plight, with Gylfi Sigurdsson taking his place, but within five first half minutes, their European campaign would be thrown in serious jepordary.
After Salah fed Streller, the veteran striker turned on a sixpence but hit effort bounced against the post, allowing Stoker to smash into an empty net.
The visitors' lead was doubled with 10 minutes of the first half remaining as Jan Vertonghen's flicked headed clearance from a right wing corner only found Frei, who nodded into the opposite corner beyond Freidel.
Stocker could have caused further embarrassment before the break, but chipped wide after he slalomed through the Spurs defence, and the Swiss side were made to pay as Parker's deflected cross allowed Adebayor to stab home from six yards.
The goal reinvigorated Spurs, and they should have leveled the tie before the break after Sigurdsson set Holtby free, but after the German lost his balance having rounded Yann Sommer, Scott Parker inexplicably shot wide.
However, Tottenham did draw themselves level after the interval as Sigurdsson darted inside and unleashed a dipping effort that left Sommer motionless.
Basel weren't content to sit on their double-away goal advantage however as Salah blazed over when put clean through and Frei's free kick was palmed away by Fredel.
The home side offered very little as an attacking force after drawing level and looked susceptible on the counter with Zoua guilty of not taking advantage, as his effort skewed wide to ensure that a single goal win for Tottenham will be sufficient to see them reach the last four.
But injuries to Lennon, William Gallas and Bale, to add to the loss of Defoe, hands Villas-Boas a major selection headache ahead of the remainder of the season, with the Portuguese boss already juggleing the club's Europa League campaign with their Champions League qualfyication ambitions.