The ex-Spur was one of the powerhouses behind Pompey's second-half comeback after they trailed to Liam Trotter's 26th-minute header.
But if Brown plays one more game for Cotterill, who wants him to take on Leeds tomorrow, he will trigger a clause in his contract that he has to be offered a new pay deal based on the £34,000 a week he earned when the club were in the Premier League.
All square: Nugent was in the right place at the right time to earn a point for Pompey at Fratton Park
'I am going back to see him now,'said Cotterill after the match. 'I want him to play at Leeds. But totake a drop in pay is a big livelihood decision. I can't make him doanything like that. He has got to want to do it.'
Cotterill also knows that Brown'snatural replacement, Richard Hughes, will trigger a similar clause inhis contract if he plays at Elland Road.
'It's not the worst position I have been in since I came here,' said Cotterill, who has been given nomoney to spend in the transfer window by owner Balram Chainrai.
'That was in August when I was looking for players, but it's pretty bad.'
Pompey laboured to contain Millwallin the first half when burly strikers Liam Trotter and Steve Morisonplayed on the indecision in Aaron Mokoena's mind after being bookedearly on.
Trotter put them ahead in agoalmouth scramble and also hit the woodwork as Millwall looked set toextend a four-match unbeaten run.
But Pompey dominated the second halfand secured a point when keeper David Forde parried David Nugent'sclose-range header into the net.
'I thought it was a fair result,' said visiting boss Kenny Jackett.
Freezing festive weather sees two Premier League fixtures called off Ramsey and Bale move closer to Olympic contention with GB teamMilan and Prada or Sunderland and Primark: Bruce explains Beckham snub
Explore more:People: David Nugent Places: Leeds