By Matt Zahn

CHICAGO (CBS) — The Bears open the preseason Saturday at Soldier Field.

CBS 2’s Matt Zahn reports they wrapped up their two days of joint practices with the Dolphins.

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Matt Nagy said Justin Fields will for sure play past halftime and maybe into the fourth quarter after what will likely be a short start for Andy Dalton.

That should have Bears fans excited. So should this guy: running back David Montgomery has shown an extra level of quickness after an offseason working on his speed.

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He says it’s his lateral quickness that’s really improved. Montgomery probably won’t play much Saturday but he seems primed for a big regular season.

His running style has caught the attention of new teammate Damien Williams.

“He runs with a chip on his shoulder,” Williams said. “I want to ask him ‘what do you got going on personally that makes you run like this?'”

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“I just try to take advantage of every opportunity,” Montgomery said. “Whenever it’s time for my career to end, I want to be sure whatever opportunity to get to go out there to show my teammates, I can show myself that I can be out there.”