Perhaps the San Francisco Giants aren't dead set on holding on to Madison Bumgarner after all.

According to Tim Brown of Yahoo Sports, the Houston Astros have engaged the Giants in trade talks for the left-handed ace, although it's not clear how much traction the Astros have gained in discussions.

In addition to Brown's report, Henry Schulman of The San Francisco Chronicle says he doesn't know why sources have been reporting that Bumgarner is off the table, saying that Giants executive Farhan Zaidi is taking calls on Bumgarner and the bullpen.

Schulman did add, however, that it would need to be “an overpay” for San Francisco to move Bumgarner.

If the Astros were able to land Bumgarner, it would obviously represent a major power shift in the American League, as it would give Houston a fearsome and largely playoff-proven trio of Bumgarner, Justin Verlander and Gerrit Cole at the top of their rotation.

Through 23 starts this season, Bumgarner has gone 6-7 with a 3.74 ERA, allowing 132 hits while striking out 140 batters over 139.2 innings of work.

The 30-year-old, who is set to be a free agent this offseason, was originally selected by the Giants with the 10th overall pick of the 2007 MLB Draft. He went on to make his big-league debut in 2009.

Since then, Bumgarner has helped lead San Francisco to three World Series titles, most recently in 2014 when he went 2-0 as a starter and came out of the bullpen to close out the decisive Game 7 against the Kansas City Royals, logging a 0.43 ERA.

Bumgarner has a lifetime 3.09 ERA.