NEW YORK (Reuters) - An out-of-sorts Novak Djokovic scraped his way to a 1-6 6-3 6-2 6-2 win over American wildcard Jenson Brooksby on Monday to move into the U.S. Open quarter-finals and three wins from tennis immortality.

Chasing a 21st major that would seal a calendar year Grand Slam, Djokovic had difficulty getting into gear against the 99th ranked Brooksby, who for a moment looked capable of derailing the Serb.