British and Irish Lions captain Sam Warburton could miss out on Saturday's tour opener against the Barbarians at Hong Kong Stadium.
The Wales skipper suffered a knock to his knee in training last week and he will be monitored during the next 24 hours.
"Sam had a slight bump in training last week and we just want to give him time before Saturday," Lions assistant coach Rob Howley told reporters in Hong Kong today.
"We will assess it over the next 24 hours.
"The bump was to his knee. It's just a bit puffy, that's all.
"There is a lot of strength in depth within the 37 (squad) players and the quality we have in the back-row is there for all to see."
Lions head coach Warren Gatland is due to name his starting line-up tomorrow morning, with Ireland lock Paul O'Connell a probable stand-in captain if no chances are taken on Warburton.
Gatland's team is set to be dominated by Wales players, who have formed the majority of the training squad available to him over the past two weeks.
Outside of the Welsh contingent, there are expected to be starts for England fly-half Owen Farrell and prop Mako Vunipola, plus Scotland lock Richie Gray.
While the Lions will not take the Barbarians lightly, their biggest challenge on Saturday could be coping with Hong Kong's heat and humidity.
Evening temperatures are currently 27 degrees, cooling just five degrees from day time, with humidity levels touching 90 per cent.
"The heat is going to take its toll and the stress they will be under will be huge, but that is something that will benefit us when we get to Australia," Howley added.
"The players might not feel like that about it this weekend, but it will put their decision-making under pressure as well, which is good for us."