Warren Gatland has admitted he replaced Liam Williams early in the second half of Wales' Six Nations win over Italy as he feared the "emotional" fullback could pick up a red card.
Williams was shown yellow late in the first half following a high tackle on Matteo Minozzi, and did not reappear as Leigh Halfpenny took his place once the sin-binning had elapsed.
A clearly dejected Williams was shown on TV walking up the tunnel to the changing rooms as Halfpenny was introduced.
"It was about sending a subtle message to him," Gatland said.
"It wasn't the plan to only play him for 40 minutes but if there was another incident with a second yellow and red card, it'd have put us under pressure."
Wales must now wait to see if the citing commissioner decides to take any action against Williams for the hit on Minozzi.
"I thought the yellow card was fair -- we had no problems with it," Gatland said.
"Whether he gets cited as a result of that ... but I was disappointed in that if he needed to make the tackle did he need to go that high?
"The thing with Liam is that he's an emotional player, it brings the best out of him.
"But we couldn't afford with that time on the clock for something else to happen.
"If he had put his hand out like Gareth did, you are potentially looking at a red card. So it was sending a subtle message really."