I can see this going either way or slight edge to Surfer. Superman is stronger and a better fighter. He's also better in combat speed of ranged and mele type. Surfer is pretty much only good at ranged combat speed. Superman is stronger than Surfer by a fair amount. He has a good ranged power. It won't put Surfer down but it will hurt. Surfer is fast enough to keep a small distance between him and Superman. His superior ranged attacks and variety of choices then seal a victory for him. Both have taken down people superior to the other so it's not so cut and dry.
Originally posted by psycho gundam
I forgot to mention it's baby Superman inside the rocket that he shrinks to subatomic size 🙂.