It was reported Spurs had a £25m bid for Grealish rejected earlier this week as Villa's new owners have insisted that the England under-21 global would not leave before the transfer deadline on Thursday.
"I think it's so hard now because it's only four hours until the end and I don't have news now", Pochettino told a news conference.
"Football is a game where you need to be clever in how you set your principles, your strategy to try to win the games". But in four hours it will be hard to sign some players.
"We have a very good squad, with very good players, and it is very hard to add players to that".
When asked about his previous comments, Pochettino said the fact the club was able to keep stars like Harry Kane and Son Heung-Min while spending £1bn on a new stadium and redeveloping their training ground was "brave".
'It is hard to understand for people in football that Tottenham didn't sign or didn't sell players but sometimes in football, you need to behave different'.
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"I am the boss and if I expect you to do something then you need to provide it".
"Of course it's hard to understand for people in football that Tottenham didn't sign or sell players, but sometimes in football you need to behave differently", he said.
"It's true our targets are always the same level as Manchester United, Manchester City or Real Madrid but for different circumstances we can't achieve that". Then with Brexit it's worse because the cost is 30 per cent more.
"If you cannot add players who can improve your squad, the most important thing is to make sure you do not lose your best player".
A new contract will see the England Under-21 worldwide move on to more than £40,000 a week at Villa Park, as Bruce keeps the young star on side in a bid to make it third time lucky and return to the Premier League come May. "I have no doubt we are going to be competitive, with or without signings".
"I am so happy with the way they came back to training on Monday".
"Then to keep the best players is to be fearless".