Sordo just behind Welshman heading into final day as Ogier lurks in third.
Elfyn Evans led Vodafone Rally de Portugal on Saturday night after day-long pacesetter Ott Tänak retired in the penultimate speed test.
Just one stage after recording his 250th fastest time in the FIA World Rally Championship, Tänak's delight turned to disappointment as he parked his crippled Hyundai i20 roadside with smashed rear suspension.
Tänak took the lead on Friday evening despite admitting he was 'fighting' his car. He was more at ease on Saturday and dominated the second leg of this fourth round. A clean sweep of wins across this morning's three special stages carried him clear of Evans and team-mate Dani Sordo.
Another quickest time stretched Tänak's lead over Evans to 22.4sec going into the second pass of the rugged Amarante test, the longest of the rally at almost 38km.
He was fastest at the interim split points, but his car's rear right wheel began to buckle. He tried to limp to the finish, but was forced to quit with less than 4km remaining.
Evans had earlier interrupted Tänak's run of stage wins and added a second in that dramatic penultimate test, but Sordo kept the pressure on.
Despite a starter motor problem which left him fearful of stalling his i20, Sordo clawed back almost six seconds in the final Porto street stage to leave the gap at 10.7sec.
"I was shocked that Dani was so strong in that last stage," admitted Evans. "It was disappointing, I tried to save the tyres for tomorrow. Today went pretty well and we should be in a good position tomorrow, but we have to remain fully focused."
Championship leader Sébastien Ogier was third, more than a minute back, after a duel with Yaris team-mate Takamoto Katsuta. Ogier demoted the Japanese driver this morning, but a half spin dropped him behind again.
He regained the initiative but, with an eye on tomorrow's final leg, Ogier's choice of hard compound Pirelli tyres meant he struggled to fend off Katsuta. He eventually ended 1.5sec clear despite a stall in the final stage.
A throttle problem hampered Gus Greensmith for most of the day. The Ford Fiesta driver climbed to fifth after Kalle Rovanperä retired his Yaris before the start of the troublesome Amarante test with a technical issue, but he could not hold off team-mate Adrien Fourmaux.
Fourmaux, who had a similar throttle issue this morning, eased ahead in the closing test to hold fifth by 6.4sec from the Briton.
Sunday's finale is focused around the iconic Fafe stage and its huge jump before the finish. The test is driven twice, the second time as the rally-closing Wolf Power Stage and offering all-important bonus points. There are five stages in all, covering 49.47km before the afternoon finish in Matosinhos.
Leading positions after Saturday
1. E Evans / S Martin GBR Toyota Yaris 3hr 07min 09.1sec
2. D Sordo / B Rozada ESP Hyundai i20 +10.7sec
3. S Ogier / J Ingrassia FRA Toyota Yaris +1min 04.2sec
4. T Katsuta / D Barritt GBR Toyota Yaris +1min 05.7sec
5. A Fourmaux / R Jamoul FRA Ford Fiesta +4min 21.8sec
6. G Greensmith / C Patterson GBR Ford Fiesta +4min 28.2sec