out of bounds

When a bad pass is thrown towards the sideline and a player goes after it and he grabs it an keeps the ball in play but his momentum carries "him" out only, can he come back in a grab the ball before anyone else touches it?

I've seen it explained this way -
You can't touch the ball, go out of bounds, then come back in and be the first person to touch it again so no, it's not legal to make a save then come back in and touch the ball first.... BUT -

Both feet have to be established in bounds before the player can touch the ball again without being called out of bounds