Gerrard has been critical of his side in recent weeks as they have fallen 12 points behind Celtic at the top of the Scottish Premiership.
But the former Liverpool captain was bursting with pride as Ryan Kent scored the only goal just after the hour mark in northern Portugal and the visitors should have scored many more.
"Super proud of the players. To a man tonight they were outstanding. I thought they were faultless, certainly out of possession," said Gerrard.
"This is no fluke. This has come from sheer hard graft."
Rangers were without top scorer Alfredo Morelos through suspension and the absence of the Colombian could have proved costly as they missed a host of big chances before the break.