The U.S. Open begins next week, but the betting favorite on the men’s side, Number 1 ranked, Novak Djokovic, will likely be prevented from competing, barring a last-minute pivot by the player or the U.S. government. On April 21, the Department of Homeland Security extended “temporary Title 19 requirements” that mandate non-U.S. citizens entering the U.S. be fully vaccinated against COVID-19 and provide related proof of vaccination upon request. “These requirements were extended in consultation with the Centers for Disease Control and Prevention (CDC) and several other federal agencies,” DHS wrote in announcing the extension. “According to CDC, vaccines remain...