Doubront (calf) will make his first rehab start at Triple-A Iowa on Tuesday, Bruce Miles of the Daily Herald reports. Doubront has been throwing bullpen sessions and facing live hitters over the past week without incident, so he'll move ahead in his recovery process by testing himself during game action. He'll be eligible to return from the DL whenever the Cubs deem his ready, but it seems likely he'll have to settle for either a long relief role or an assignment to the Triple-A rotation once activated.