Runners on first and third. One out. Batter flies out on deep fly ball to the left fielder. Runner on third tags up and advances toward home while the runner advancing from first retreats back toward first base. After the runner on third touches home, the runner on first is called out because the fielder tags first base before the runner is able to get back. Does the run count?

Answer: Yes, the run counts. The runner from third touches home before the third out and none of the exceptions to this general rule apply in this case. Putting out the runner on first before he retouches is not a force out.

Under Official Baseball Rules 4.09 HOW A TEAM SCORES.
(a) One run shall be scored each time a runner legally advances to and touches first, second, third and home base before three men are put out to end the inning. EXCEPTION: A run is not scored if the runner advances to home base during a play in which the third out is made (1) by the batter-runner before he touches first base; (2) by any runner being forced out; or (3) by a preceding runner who is declared out because he failed to touch one of the bases.

Under Official Baseball Rules 2.00 A FORCE PLAY is a play in which a runner legally loses his right to occupy a base by reason of the batter becoming a runner.