Five 49ers to keep an eye on in Saturday’s preseason opener vs. Broncos

SANTA CLARA — The 49ers’ joint practice with the Denver Broncos on Thursday was for the headliners.Now, the focus turns to the players who are battling for roles on the team.Do not expect to see much — or any — of Brock Purdy, Christian McCaffrey, George Kittle, Trent Williams, Nick Bosa and Fred Warner.Do expect to see the rookies and other players who are looking to make impressions when the 49ers take on the Broncos at Levi’s Stadium on Saturday evening in the first preseason game for both teams.Here are five 49ers to watch as the jockeying continues for roster spots and roles on the team:CB Jakob RobinsonRobinson, an undrafted rookie from BYU, might lead the team in passes defensed through 12 days of practices leading up to this exhibition game.Robinson took advantage of increased practice time against better competition. He moved up a spot with starting cornerback Renardo Green out for a couple of weeks with a hamstring injury and Deommodore Lenoir sidelined for a three-day block due to hip irritation.Robinson should get an opportunity to see a lot of action against a different set of wide...