Steve Bruce has confirmed Dwight Gayle is facing up to four months out with a knee injury.
Gayle had a scan on Friday after injuring his MCL last week at Newcastle's training camp in York.
The 29-year-old made 22 appearances for Newcastle last season, scoring four goals in the Premier League.
The injury to Gayle has accelerated Bruce's move for Bournemouth striker Callum Wilson.
Newcastle have tabled a bid totalling £20m for Wilson while Aston Villa have upped their offer to £21m.
Villa made an improved bid after their £15m offer (plus add-ons) was rejected by the Cherries on Friday.
The Newcastle bid has not been accepted or rejected. However, a source close to Wilson says he favours a move to Tyneside.
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The England international is keen for a move to either club and wants to play Premier League football next season.
Wilson has scored 67 goals in 180 Bournemouth appearances since joining the club from Coventry in 2014, with eight of them last season as the south coast club were relegated from the Premier League on the final day.
The 28-year-old has also attracted interest from Fulham, West Ham and Tottenham this summer.
It is understood Bournemouth want Matt Ritchie from Newcastle in a separate deal, but wages may be an issue.
Newcastle stepping up transfer efforts
Newcastle are stepping up their efforts in the transfer market having had a £13.5m bid accepted by Norwich for Jamal Lewis on Saturday.
They have also been in negotiations with Sassuolo for left-back Rogerio, according to Sky in Italy. A fee of £12.5m is being discussed for the 22-year-old.
Newcastle have also been actively trying to bring free-agent forward Ryan Fraser to the club this week.
The Scotland international, who ran down his contract with Bournemouth, was on Tyneside on Friday to hold talks with Newcastle boss Steve Bruce.
Fraser has not yet decided on his future and no agreement is in place with Newcastle. However, it is believed the 26-year-old is keen to move to St James' Park.
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The summer transfer window will run for 10 weeks from July 27 and close at 11pm on October 5.
A domestic-only window for trades between the Premier League and EFL then runs from October 5 and closes on Friday, October 16 at 5pm.
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