Robertson replaced his fellow left-back on 38 minutes at Turf Moor after manager Arne Slot made the decision following a booking received by Kerkez for diving.
After the late 1-0 win, Robertson said: “He has come in and was fantastic for Bournemouth last season.
"He's only young and I think we forget that, all the new signings are young but have incredible potential and they are the future of the club and you try to help them as much as you can.
"But you want to put pressure on them and you want to play games.
"He will be the starting left-back for Liverpool in the future and it's up to me to push him this season and help him improve. He has a fantastic future ahead of him and he just needs to keep working hard and not let (Sunday) affect him, which it won't as he's a confident lad."
Robertson also recalled: “It's a massive jump.
"I came from Hull, he's come from Bournemouth and it's probably quite similar. There are a lot more eyes on you in a Liverpool jersey than it is than those two clubs.
"He has transitioned well, there's a lot of information and a lot of different ways of playing and he just needs to keep going and keep his confidence.
"We'll try to help him and others throughout the season and I have no doubt in the future he will be a fantastic left-back for Liverpool and that's the main thing."