Newcastle United will likely be sweating on the fitness of midfielder Bruno Guimaraes, following concerning reports from Brazil's World Cup camp.

What's the word?

According to UOL, the 25-year-old reportedly sustained a knock during training in preparation for the upcoming tournament in Qatar, having been seen leaving the pitch after sustaining a blow to his left foot.

The report suggests that while the former Lyon man - who arrived at St James' Park on a £40m deal in January - did return to action later in the session, the eight-cap sensation was seen 'limping and looking uncomfortable' from then on.

While it is not yet known whether it is a serious issue at this stage, there may well still be concern among those back on Tyneside, particularly with the competition having yet to even get underway.

Howe must be worried

Newcastle boss Eddie Howe will no doubt be worried to see his star asset sustaining a blow while on international duty, with it set to be an anxious next few weeks for the 44-year-old as a handful of the club's key figures get set to take to their field for their respective nations.

The loss of Guimaraes, in particular, would be a notable blow for the northeast side when club action resumes at the end of next month, with the midfield maestro having been in stunning form since his move to England earlier this year.

The £120k-per-week machine - who has been mooted for a bumper new deal in recent times - has been a central figure in the club's surge up the Premier League table, having impressively scored three goals and laid on two assists from his holding role so far this season.

That follows what was a sparkling end to last term for the Rio-born menace as he scored five times in just 17 league games to make an instant impression in his new surroundings, having notably been lauded as a "world-class" asset by teammate Dan Burn in recent times.

To lose such a highly-regarded presence could well be a significant blow to the club's hopes of securing a Champions League berth, with Howe's men having failed to win any of three top-flight games that Guimaraes was absent for due to a hamstring issue earlier this term.

That has illustrated the 6-foot ace's undoubted importance to the Magpies, hence the concern that this latest knock escalates into something more serious.