Guardiola left De Bruyne out for the 1-0 away defeat in the first leg of their Champions League quarter final against Tottenham.
But he was back and starring as the Sky Blues defeated Crystal Palace in the league.
"Palace help Kevin De Bruyne in the first half - there is lethargy about their performance," Murphy said on Match of the Day 2.
"They are too passive and didn't lay a glove on City.
"De Bruyne has the creativity to open anyone up. Whether a cross, set play or through ball they're all in the locker.
"Man City are still top of the league without him for most of season and that's credit to the players, but he makes them a better team. He's going to be pivotal for them in these last few weeks of the title race and European run.
"Pep's got a nice problem in mid-week with the quality he has to choose from, but for KDB has to be that first name on the team sheet now."