The wide receiver started with the first-team offense at Candlestick Park, but did not make a reception for his new team.
The 32-year-old told the Broncos' website: "We've been seeing the same guys for the past month or so and we're just ready to get out there and play against somebody else. It was good to see and good to have that competition going against another team.
"It's early and I've had a lot of pre-seasons where I had no catches going into the year. It's just a matter of us getting our execution down and things like that.
"Just some of the mistakes that we made, trying to correct those and move it on to next week and just try to move it all together. You don't really get to get into that flow but it's just one of those deals you try to move forward with and make the best of it."
Welker joined the Broncos during free agency after turning down a new deal with the New England Patriots.