Jose Mourinho looked to have his summer's transfer business all wrapped up following the world record move of Paul Pogba from Juventus to Manchester United at the start of August.
He said: "The transfer window is closed in the U.S. so I'm not going there now".
"We have to wait to see what happens in September and October and how things will develop, but I will definitely not stop playing football".
Bastian Schweinsteiger says a move to a MLS club in the United States is an option if he can not regain a place in the first team of Manchester United.
The move to the KCOM Stadium sees Keane reunited with former United assistant manager Mike Phelan who is now in temporary charge of Hull following the departure of Steve Bruce over the summer.
The 18-year-old gave yet another complete performance as he came on with around 20 minutes left and scored the only goal of the game in stoppage time against Hull.
Keane joined United as an 11-year-old and made his senior debut in December 2011 against Blackburn.
Keane played against the Tigers twice during a loan spell with Preston North End last season and has been impressed with the way they have taken to life back in the top division.
"Mourinho showered (the 34-year-old Zlatan) Ibrahimovic with praise for still playing and if I get a fair chance, I believe in my abilities".
"People will judge me on the goals I score, so that is what I want to do".
"With him being a centre half, hopefully I'll be directly up against him".
This move could be fantastic for Will and I hope it really works out for him.
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