Del Potro broke Berlocq's serve twice in the second set and closed out the match in 1 hour, 6 minutes. After Tuesday's three-set victory over Marcos Baghdatis, del Potro said it was good to find his rhythm.
"I played a lot better than yesterday," del Potro said. "I served well, my forehand was strong, and I was able to break his serve and be aggressive. I had control of the match all the time, which was important to me."
Del Potro was a late addition to the tournament after Andy Murray, the 2011 champion, withdrew due to a back injury. Del Potro is seeking his third title of the season following victories in Rotterdam and Washington.
Raonic, coming off a win at the Thailand Open on Sunday, dominated Soeda with his serve, hitting 24 aces against the Japanese wild card.
"I served really well," Raonic said. "It was a bit earlier in the day than what I'm used to but I played well on the important points and did what I needed to do."
The fourth-seeded Nishikori is on the verge of becoming the first Japanese player to break into the top 10 and is bidding to win his second title of the season.