Wales international Morison grabbed his 13th goal of the season to keep the Lions on course for the npower Championship play-offs.
James Henry drove in a low cross from the right and Morison was on hand to steer the ball inside the far post to put Millwall on their way to a 2-0 victory over Barnsley.
On target - again: Millwall's Steve Morison is wanted by two Premier League clubs
The Lions are desperate to hold onto their top scorer, who has been linked with Fulham and Wolves, and Jackett may be tempted to switch his phone off between now and the close of the transfer window on Monday evening.
But a new two-and-a-half-year deal is on the table and Jackett said: 'We've talked to Steve. I don't know at what stage those guys are at but we are in negotiations.
'It was a good finish, he kept it down well on his left foot outside the post. It was an easy one to miss on your wrong foot and it was the vital first goal.'
Henry added a second eight minutes before half-time with a 20-yard drive which took a wicked deflection off Tykes full-back Matthew Hill.
The second half was something of a non-event but Jackett was not complaining after a fourth straight home win which moved his side up to eighth, just three points shy of the top six.
'It was a very good start and a good win after the defeat at Leicester last week,' he added.
'The second half was a bit surreal but we saw it through. We don't want to get too far ahead of ourselves. It's the old adage of taking each game as it comes, and if we are still up there in March then we can start looking in the right direction. You have to look short term in this industry.'
It all added up to a second wasted trip to south London in the space of a month for the 270 hardy Barnsley fans after the original fixture was called off a couple of hours before kick-off.
Their team nearly gave them something to cheer in the 15th minute but Hugo Colace fired over from 12 yards.
Jacob Butterfield could have dragged Barnsley back into the game with 10 minutes remaining, but their chances disappeared along with the midfielder's shot as it flew wide.
'It took us two goals to get going,' said Tykes manager Mark Robins. 'We were lacklustre. You know when you come to The Den about Millwall's energy and that they work hard, but we didn't get to grips with it.
'We were a soft touch, which was disappointed. But it was our third game in six days and it's taken its toll.'
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