LOUISVILLE, Ky. - These are some pretty eventful times for race-caller Mark Johnson.\nHis mother died in October following a lengthy illness. He married his sweetheart, Katherine, on a Caribbean island in January. He called the world-renowned Grand National steeplechase in his native England in early April. A week or so ago, he flew from England to America for a lengthy stay.\nAnd, oh yes, a week from Saturday, he will call his first Kentucky Derby for an ontrack crowd of some 150,000 screaming fans.\nJohnson, who was named the Churchill race-caller in January after he and four other men auditioned for the job at the 2008 fall meet, finds it hard to believe what is happening with his life.\n"I haven't had a period like this in my life ever before," Johnson, 43, said in knowing understatement.\nFor someone who has practiced calling races since he was a tot, the prospect of calling the Derby is a dream come true. Johnson, who called his first race as a professional in 1986 and since has become a widely known race announcer and television commentator in England, said simply trying out for the Churchill job last November "was one of the highlights of my entire career. To win it was hugely, hugely surprising to me."\nPredictably, Johnson's calls are liberally sprinkled with what he calls "Britishisms," the peculiar sayings that are largely unfamiliar to American racing fans - especially those in Kentucky, where a Southern dialect is most prevalent. Churchill officials have said repeatedly they foresee no problem with this mixing of cultures and that Johnson was a clear-cut choice for the job by fans.\nOne issue that surfaced during Johnson's four-day stint here last fall was that he tended to talk considerably more than other announcers - before, during, and after races with his own commentary, and then with obligatory between-race announcements, promotional and otherwise. At times, it made for a cycle of almost ceaseless chatter.\n"We have talked about that a little, and I am hoping that perhaps we can cut down on some of that," said Johnson.\nWhile Tom Durkin will call the 135th Derby for millions of worldwide television viewers for NBC Sports next Saturday, it will be Johnson's call that is piped throughout the Churchill plant and into thousands of simulcast outlets in North America and beyond.\n"I will be nervous," said Johnson. "If I weren't, I don't think I would do as good a job. Announcing, you work on adrenaline. If it's the Derby or a rainy Wednesday at Wolverhampton back home, there's not a day that I go into the booth that I don't get nervous. The day I stop tingling is the day I stop doing this. It's a passion, a hobby, something you love doing, and you really pump yourself up for it."\nWhen he calls the first race on the opening-day card Saturday, Johnson will become the sixth race-caller in Churchill history. He was preceded by Gene Schmidt (1940-60), Chic Anderson (1960-77), Mike Battaglia (1978-96), Kurt Becker (1997-98), and Luke Kruytbosch (1999-2008), who died suddenly last July, apparently of a heart attack.\nJohnson arrived April 16 in Louisville and has been out and about on the Churchill backstretch in recent days, submitting to interviews with the media and introducing himself to horsemen, fans, and other members of the racing community. He has been struck by how well-liked Kruytbosch was.\n"Luke is a hard act to follow," he said. "He was a great human being as well as a great announcer."\nJohnson knows it will take years to earn a similar measure of respect and endearment from those same people, but he is more than willing and eager to get started.\n"I was on cloud nine last fall, just being here for those four days," he said. "I can't imagine how great this is all going to be."