Google Inc. is removing text ads from the right side of its desktop search results pages. At the same time, the search engine says it may show users four ads above search results for what it calls “highly commercial queries”—such as Chicago hotels—rather than the three it had been showing.

“We’ve been testing this layout for a long time, so some people might see it on a very small number of commercial queries,” a Google spokesman says. “We’ll continue to make tweaks, but this is designed for highly commercial queries where the layout is able to provide more relevant results for people searching and better performance for advertisers.”

With the change, Google will only place ads at the top and/or bottom of the search results page, with the exception of Product Listing Ad boxes, which show up above or to the right of search results, and ads in Google’s Knowledge Panel, which presents information about a local business, such as its phone number, address and hours of operation.

The move will put more pressure on retailers to increase their bids for their most important keywords to ensure consumers see their paid search ads, says Holly Pauzer, client insights and research manager at digital marketing firm Adlucent.

“Brands should expect competition for the top three spots on the results page to increase and CPCs [cost-per-click prices] to follow,” she says. “Advertisers will need to be more granular in their build-out to be eligible for more auctions and should turn to tools like Google’s Customer Match to target the right consumers and retain efficiency.”

Google’s move will also increase the importance of PLAs, writes Bradley Hearn, content marketing strategist at ChannelAdvisor Corp., in a blog post.

“PLAs will continue to grow in popularity, and more retailers and brands will continue to slug it out for those top spots,” he writes. “We’ve already seen that Google is experimenting with an expanded PLA layout that could bring the number of PLAs on the SERP [search engine results page] to 16. Any way you look at it, PLAs are a big part of most retailers’ future.”