Lawyer deliberately left out one page of a PDF document sent over in discovery

I am currently in a lawsuit. The opposing side's lawyer intentionally left out one page of a PDF document in his discovery documents. This single page left out was something that would hurt his case tremendously and strengthen our case. The document was the CCRs for an HOA. It is available for download on the HOA website. I had downloaded the same document myself when researching and found this page which strengthens our case. He would have had to deliberately edit the PDF to leave out that page. I was shocked a lawyer would actually do this and just thought we wouldn't do our own research I guess. What is the recourse for this? Lawyers shouldn't get away with something like this. Has anyone had something similar happen to them? Any lawyers on this subreddit to weigh in?