Ireland captain Rory Best looks set to miss Ulster's opening two European Champions Cup games next month after suffering a hamstring injury.
Best, who skippered the British and Irish Lions' midweek team in New Zealand this summer, was hurt during training last week and Ulster have now confirmed that the 35-year-old hooker will be sidelined.
"Following a scan, it has been confirmed that Rory Best has a hamstring tear and will be out of action for approximately four to six weeks," Ulster said in a statement.
Ulster launch their Champions Cup campaign against Wasps in Belfast on October 13, then travel to French club La Rochelle nine days later.
Ireland's opening Test of their autumn series is against South Africa on November 11, followed by appointments with Fiji and Argentina.