The injury came in just his fifth appearance since returning from an eight-month lay-off following surgery on his other knee.
Related ArticlesHull optimistic on Bullard scanAston Villa 3 Hull City 0Bullard's celebration one of the bestBrown applauds Bullard's celebrationManchester City 1 Hull City 1Sport on televisionBullard and Hull feared the worst but, after a scan on Monday night, manager Phil Brown was relieved that the injury was not as serious as first thought.
'I am sitting here like a man waiting in the emergency room for his wife to give birth,' Brown said.
'It's been an horrendous day for me but you talk about popularity the amount of well-wishers and people asking about Jimmy, it is fantastic the response to one of the most popular players in the country.
'I'm now very hopeful Jimmy will be back on the field of play before the transfer window closes.
'That's what I and Jimmy will be looking at. It also gives us a chance to strengthen his other leg it hasn't been a problem but it gives us a chance to strengthen. Hopefully we'll have him for three to four months of the season still.'
Bullard marked his full Hull debut with a starring role in the 2-1 win over Stoke. The £5 million signing from Fulham then scored in draws with West Ham and Manchester City, the latter being met with a choreographed celebration mimicking Brown's famous half-time team talk on the pitch at Eastlands last season.
'He's a tremendous character, the way he is he just wants the ball and to please people,' Brown added.
'He's that kind of character, there are not so many about.'
David James is confident of a return for Portsmouth at Sunderland on Saturday after overcoming a calf strain.