Malaga maintained their unbeaten start to the season when teenager Juanmi came off the bench to rescue a 1-1 draw at home to Real Mallorca on Saturday.
The stalemate at the Rosaleda meant Malaga, who had Eliseu sent off late, missed the chance to join Rayo Vallecano on six points at the top of the standings after the Madrid club won 2-1 at Real Betis in the earlier kickoff.
Rayo's Brazilian-born teenager Leo, who turns 20 on Sunday, drove home the winner half an hour from time in Seville having set up Piti to score in the second minute before Jorge Molina levelled for Betis two minutes later.
"It's a dream come true," Leo told reporters.
"I just did what I know best, play football," he added. "But we have to keep a clear head and keep working just as hard."
Barcelona can join Rayo on six points from two matches with a win at Osasuna on Sunday, while champions Real Madrid are looking to bounce back from last weekend's La Liga draw at Valencia and Thursday's 3-2 defeat at Barca in the first leg of the Spanish Super Cup when they play at city rivals Getafe.
Malaga have made a bright start to the season despite seeing Spain midfielder Santi Cazorla and Venezuela striker Salomon Rondon depart for Arsenal and Rubin Kazan respectively.
The Andalusian club have said they are going through a process of "internal restructuring" and there has been widespread speculation their Qatari owner is looking to sell up after only two years.
Malaga qualified for the Champions League for the first time last term and will make it into the group phase if they protect a 2-0 lead in their play-off second leg at Greek side Panathinaikos on Tuesday.
Mallorca's Israeli forward Tomer Hemed netted a 67th-minute header to give the Balearic Islanders the lead against the run of play on the south coast, in a match that kicked off at 11 p.m. local time to minimise the summer heat.
Juanmi, who was born in Malaga and came through the club's youth academy, equalised for the home side when he skipped on to Francisco Portillo's pass in the 76th minute and poked the ball past Dudu Aouate in the Mallorca goal.
Eliseu, another second-half substitute, was shown a straight red card a minute from time after he tangled with midfielder Pina.
In the earlier kickoffs, Portugal forward Helder Postiga netted an 89th-minute winner for Real Zaragoza in a 2-1 win at Espanyol, who had Juan Albin sent off for a second yellow card five minutes after the break.
Real Sociedad recovered from their 5-1 thrashing at Barca in their opening match of the season to inflict a second straight defeat on promoted Celta Vigo.
The Basques had to come from behind at their Anoeta stadium in San Sebastian after Enrique De Lucas fired Celta ahead in the 49th minute.
Imanol Agirretxe equalised five minutes later and a mix-up between two Celta defenders shortly after allowed the home-grown forward to steal in and score the winner from close range.