At the age of 21, Tull signed for Football League First Division team, Tottenham Hotspur, in the summer of 1909, after a close-season tour of Argentina and Uruguay, making him the first mixed-heritage professional footballer to play in Latin America. Tull made his debut for Tottenham in September 1909 at inside forward against Sunderland and his home Football League debut against FA Cup-holders, Manchester United, in front of over 30,000. His excellent form in this opening part of the season promised a great future. Tull made only 10 first-team appearances, scoring twice, before he was dropped to the reserves. This may have been due to the racial abuse he received from opposing fans, particularly at Bristol City, whose supporters used language "lower than Billingsgate", according to a report at the time in the "Football Star" newspaper. The match report of the game away to Bristol City in October 1909 by "Football Star" reporter, "DD", was headlined "Football and the Colour Prejudice", possibly the first time racial abuse was headlined in a football report. "DD" emphasised how Tull remained professional and composed despite the intense provocation; "He is Hotspur's most brainy forward ... so clean in mind and method as to be a model for all white men who play football ... Tull was the best forward on the field." However, soon after, Tull was dropped from the first team and found it difficult to get a sustained run back in the side.