Diamondbacks 1B Christian Walker (oblique) exits game

(Photo credit: Kamil Krzaczynski-USA TODAY Sports)

Arizona first baseman Christian Walker exited the Diamondbacks' Monday game against the Washington Nationals in Phoenix due to left oblique tightness.

Kevin Newman replaced Walker at first base at the top of the fourth inning.

It wasn't known when Walker was injured, but in the third inning he made a long run down the first base line into right field to catch a foul pop