Well, then. The Arizona Cardinals' competition for Peyton Manning has grown to include a division rival.

Manning worked out for San Francisco 49ers coach Jim Harbaugh and took a physical for the team this week, according to ESPN's Chris Mortensen.

This does not necessarily make the 49ers a favorite for Manning. It could help explain why the 49ers have not quickly re-signed Alex Smith during the opening days of free agency, despite a longstanding pledge to bring him back for 2012 and beyond. The 49ers' involvement, rather than causing a delay with Smith, might also reflect the state of negotiations. It is possible Smith is asking for more money than the 49ers are offering, leading the team to explore options that could, in turn, bring Smith back to the table.

Manning and Smith share the same agent, Tom Condon, further affecting dynamics. Smith presumably is not surprised by these developments, in other words.

The 49ers are emerging publicly as a factor just as the Arizona Cardinals' chances for Manning appear to be diminishing. Arizona must decide by 4 p.m. ET whether to pay a $7 million bonus for incumbent quarterback Kevin Kolb. Failing to pay the bonus would make Kolb a free agent, leaving John Skelton and Rich Bartel as their only quarterbacks under contract.

The 49ers, unlike the Cardinals, face the looming deadline with Smith. But it's now a fact that Manning is affecting three offseasons within the NFC West. Seattle reached out with strong interest, only to have Manning show no reciprocal interest. Arizona secured a meeting with Manning, only to spend this week waiting for a response. Now, the 49ers are in the mix.

Fun, fun stuff. More to come.

Update: More here.