Poor defending from Gerard Pique and Gabriel Milito let Gijon striker David Barral in to score in the 16th minute at the Molinon before David Villa equalised against his former club with an exquisite chip 10 minutes from time.
The champions spent almost the entire match in the Gijon half but were thwarted time and again by the home side's resolute defence and not even World Player of the Year and joint La Liga top scorer Lionel Messi could find a way through.
"We managed in the end to get the draw and we should make the most of the point," Spain striker Villa said in a television interview.
"Barcelona cannot be satisfied with a draw because we like to win but it's true that Sporting were superior in many respects."
It was only the third time Barca have dropped points this season and spoiled their perfect record away from home.
WILD CELEBRATION
In Saturday's other matches, Atletico Madrid's chances of qualifying for Europe receded when Diego Forlan fluffed a penalty and former Spain winger Joaquin struck twice to give Valencia a 2-1 comeback win.
Racing Santander produced a thrilling performance for new Indian owner Ahsan Ali Syed, who was shown on television celebrating wildly in the VIP section of the Sardinero stadium as his team survived being reduced to 10 men just before half-time to snatch a last-gasp 3-2 win over Sevilla.
The Andalusian club, who also had an Alvaro Negredo penalty saved, came from two goals down to level at 2-2 before Manuel Arana caught goalkeeper Andres Palop off his line with a superb lob to send Ali Syed and the home fans into raptures.
Atletico have now suffered four consecutive league defeats and pressure is mounting on coach Quique Sanchez Flores.
Jose Antonio Reyes gave the Europa League champions an early lead at the Calderon with a third minute strike before Joaquin stole in for the equaliser just before halftime.
Forlan, who has been given a hard time by Atletico's demanding fans in recent weeks, stepped up to take a 58th-minute spot-kick after Reyes was brought down but the Uruguay striker smashed his effort against the post and the ball flew to safety.
Both sides had chances before Valencia captain Joaquin capped a fine performance when he arrowed a powerful low drive into the bottom corner for the winner in the 86th minute.
Atletico's woes were compounded late on when Forlan's Uruguay team mate Diego Godin was shown a straight red card after he caught Joaquin with a stray arm.
Valencia's victory lifts them into third above Villarreal, who play at struggling Deportivo La Coruna on Sunday. Atletico are eighth on 30 points, seven behind sixth-placed Espanyol.
Racing's victory lifts them to 12th, although they are still only four points above the relegation places, while Sevilla stay a point above Atletico in seventh.
