Murphy is the man in form having won the Haikou World Open in China this month, and is targeting back-to-back ranking event titles this week at the Guild Hall. In fact the match against Robertson saw plenty of mistakes from both players, but it was Manchester-based Murphy who proved stronger, making top breaks of 70 and 64.
"My record against Neil isn't good, in fact when a friend of mine found out I was playing him in the first round, he said he wouldn't bother coming!" said Murphy. "I thought the game was scrappy tonight. We both gave it everything.
"I've got four massive matches to go now in this tournament but all I can do is focus on the next one. I'll go home and practise and hope to come back fresh. It's fantastic being back at the Guild Hall, this place is full of heritage.
"It was great to win in China and end a long wait for a title. I knew I was playing well enough."
It doesn't get any easier for Murphy as he now plays Judd Trump, who beat Chinese amateur Ju Reti 4-1. Ju started well with a break of 75, but Trump then dominated with runs of 56, 76, 86 and 80.
"Ju has been practising at the same place as me and I knew his safety was not great so I expected to get chances," said Trump. "I played ok but I'll have to play better against Shaun.
"It looks like every match here is going to be against one of the top players, but I've had easier draws this season and not got through, so maybe I'll raise my game against the better players. This is the best line-up we've had for this tournament. It's a nice arena and I'm glad the tournament is in the UK. The conditions were good and it was nice to have a few people in there."
Gerard Greene, who earned his place in Preston with a run to the final of the Paul Hunter Classic last August, scored a surprise 4-1 win over world number 11 Ricky Walden, his top runs 61 and 50.
Marco Fu top scored with 102 in a 4-0 defeat of Gary Wilson.
Ball by ball scoring and results from tournaments