England striker Michael Owen is likely to miss Newcastle's Barclays Premier League opener at Bolton next Saturday.
Owen's Newcastle career has been dogged by injury setbacks
Boss Sam Allardyce, who signed Alan Smith from Manchester United on Friday, admits Owen's torn thigh muscle "hasn't healed as quickly as we would like".
"It doesn't look as encouraging as we first thought," he told the Daily Mail.
"There's no point in making any rash decisions just to get him fit for the start of the season. It's about getting him 100% to play on a regular basis."
Owen, whose career on Tyneside has been beset by injuries, played just three times for the Magpies last term and has made just 14 appearances since his transfer from Real Madrid in December 2005.
The injury has already wrecked the 27-year-old's pre-season programme.
"It has been more disappointing for him that he's missed pre-season games more than training," Allardyce added. "He's done enough training to last him a lifetime."
The latest setback also puts in doubt Owen's participation in England's friendly with Germany at Wembley on 22 August.