The Yankees aren't wasting any time looking for a replacement for third baseman Alex Rodriguez. On the first day of baseball's free-agency period, the Yankees have opened serious discussions with the agent for third baseman Mike Lowell, said a person close to the negotiations who spoke on condition of anonymity because of the sensitive nature of the discussions. The Yankees would prefer to acquire a third baseman through free agency instead of via a trade because they would not like to give up their young pitchers for a position player such as the Marlins' Miguel Cabrera. If Lowell re-signs with the Red Sox or another team, however, the Yankees might have no choice but to explore their trade options.