CLEVELAND -- There is a seat in the Progressive Field press box that belongs to the legendary Bob Feller. It sat conspicuously empty during the Indians' current homestand, as the senior member of the National Baseball Hall of Fame battled leukemia.On Sunday afternoon, as the Indians finished up a three-game set with the Royals, the man known as "Rapid Robert" was back in that seat, talking about his bout with cancer and, of course, talking ball. The 91-year-old Feller said he was diagnosed with acute myeloid leukemia less than two weeks ago. It is a form of cancer in which abnormal white blood cells interfere with the production of normal blood cells. "I took about two quarts of blood," Feller said. "My blood was down. I only had about half as much blood in my system as I'm supposed to have." Feller spent two days at the Cleveland Clinic, followed by a week's worth of outpatient care that involved regular chemo shots. "So far, the evaluation is that I have not felt tired and don't need any more blood," Feller said. "We're very encouraged that everything is going to be all right. But it's going to take another two weeks or a month to really know exactly what's going on. But I'm going to see the doctor [on Monday] and have some more evaluations." It was no surprise that the moment he was feeling better, Feller returned to the ballpark. Decades after his remarkable pitching career came to a close, the game still has a strong pull on him. Feller made his Major League debut with the Indians in 1936, at the age of 17, after growing up in the Iowa cornfields and catching the eye of scout Cy Slapnicka. After signing with the Tribe for $1 and an autographed baseball, Feller went on to pitch 18 seasons for the Indians, going 266-162 to set the team record for victories. He led the American League in strikeouts seven times, was an eight-time All-Star, pitched three no-hitters, including the only Opening Day no-hitter in history, and 12 one-hitters. He missed three years of his prime while serving in the Navy during World War II. Feller was inducted into the Hall of Fame in 1962. He is the third-oldest living member of the Hall and the longest-tenured living member. Feller, usually an indefatigable sort, had been feeling tired in the days and weeks leading up to the discovery of the ailment. "I thought I had a heart problem, but I was completely wrong," he said. "My heart's in very good shape. But it was the blood problem, leukemia. And it is treatable. Hopefully it works."