Shock Spanish title challengers Girona returned to the top of La Liga with a 1-0 at Celta Vigo on Sunday.
Atletico Madrid climbed third, above struggling champions Barcelona on goal difference, with a comfortable 2-0 win at home against Valencia.
Michel Sanchez's Girona moved one point clear of Real Madrid, who beat Las Palmas on Saturday, although the Catalan team have played one more match.
Portu finished well in the 20th minute to send Girona ahead in a match they largely dominated but could not make safe by finding a second goal.
Rafa Benitez's Celta sit two points above the relegation zone in 17th place.
Girona, in the top flight for only the fourth season in their history, continue to battle with Spain's giants for La Liga.
"We knew we had to take advantage of the chances we had, in the first half we made a lot of chances to score, they had some too," said Girona winger Portu.
"At this stage of the league the important thing is three points and competing."
Girona players and staff have been reluctant to admit the team is in contention to win the title.
"The main thing for us is that we shouldn't be thinking too far ahead, that would be a mistake," added Portu.
"We know that we are leaving teams behind us to get into the European places, we have to be realistic, and that's our objective."
On a rough pitch at Celta's Balaidos stadium, Girona took the initiative from the start.
"We had a lot of personality to keep the ball in conditions that were difficult to play on," said Girona coach Michel.
"They had chances, as did we, but I think we were fair winners."
Yangel Herrera hammered into the side netting as an early warning and Celta goalkeeper Vicente Guaita kept out an Artem Dovbyk header.
The Ukrainian, La Liga's joint top goalscorer with Real Madrid's Jude Bellingham on 14 goals, came close on other occasions but could not add to his tally.
Girona's Paulo Gazzaniga saved well from Oscar Mingueza before his team took the lead.
Miguel Gutierrez found Portu, who manoeuvered well and stroked home at the near post.
Viktor Tsygankov fired over after being teed up by his compatriot Dovbyk at the end of a slick team move.
Celta threatened through Jorgen Strand Larsen, who headed against the crossbar, but that was as close as they came to an equaliser.
Girona tightened up defensively in a hard-fought second half and Celta could not carve out any clear chances as the clock ticked down.
Controlled the game
Champions Barcelona, fourth, lost 5-3 at home against Villarreal on Saturday, after which coach Xavi Hernandez said he would leave the club in June.
Atletico eased above them with Samuel Lino and Memphis Depay on target against Valencia, eighth.
Lino, who played at Valencia on loan last season, finished clinically after Antoine Griezmann found him with a superb pass.
Depay added the second in the 57th minute with a diving header from Nahuel Molina's cross, after midfielder Koke sprayed the ball out to the right flank.
"We controlled the game very well as a whole," said satisfied Atletico coach Diego Simeone.
Reinildo Mandava made his first start for Atletico after injury.
"It makes me very happy, the group really loves him," he added.
The coach said striker Alvaro Morata had some thigh discomfort and would be tested on Monday.
Simeone left new arrival Arthur Vermeeren on the bench after his recent move from Royal Antwerp, while Juventus striker Moise Kean watched on from the presidential box ahead of his own impending move to Atletico.
Athletic Bilbao, fifth, were held to a 0-0 draw at Cadiz, while Sevilla failed to secure a home win for the eighth time in a row in the league, with a 1-1 draw against Osasuna.
