Uruguay coach Oscar Tabarez has confirmed Diego Godin is doubtful for Friday's quarter-final clash with Ghana.
The Villarreal defender has been a lynchpin in the back-line that has conceded just one goal in four matches so far in South Africa.
But the 24-year-old, who has already made 41 international appearances, sustained a thigh injury in the 2-1 win over South Korea and had to be replaced at half-time.
He trained separately for the first 15 minutes of Monday's session, jogging round the pitch with Diego Forlan and Diego Perez, and asked on Tuesday about Godin's condition, Tabarez said: "It is the doctor who should be speaking.
"He (Godin) is recuperating and we still don't know if he will play or not."
Should he fail to recover in time, Mauricio Victorino is set to start after replacing Godin and putting in a solid performance in the second half.
Forlan has a bruised toe while Perez had stitches for a cut from the South Korea game but Tabarez confirmed that both are fit to play against Ghana.
Uruguay have reached the last eight for the first time in 40 years and have a great chance of going one step further with Ghana making their first quarter-final appearance and being 16 places below them in the world rankings at 32.
Uruguay won the World Cup back in 1930 and 1950 and the country's three million people are desperate for a return to the glory days.
"It is an important game for the Uruguayan nation but, for me, I don't like to think about this," said Tabarez.
"I like to concentrate. It is not good to think too far ahead."
Uruguay have completed their preparations for the Ghana game and will fly out of Kimberley, their base camp, for Johannesburg on Wednesday afternoon.