Scotland head coach Gregor Townsend has backed his side to bounce back from their defeat to Ireland in their first match of the Rugby World Cup, despite admitting his players lacked "energy and aggression".

Ireland were comfortable in their 27-3 win in Yokohama with Scotland's only points coming from a Greg Laidlaw penalty. Townsend rued the opposition's ruthlessness in punishing mistakes but also said that his own side were lacking from the start.

"It was disappointing, we didn't start with the energy, accuracy or aggression required to beat a team like Ireland," he said. "They started very well and took their chances when they got into our 22.

"They're one of the best teams in world rugby and if you give them a 15 to 20 point start it's going to be very difficult to come back.

"They just converted mistakes into territory, mistakes into points directly.

"We need to win our next three games, whatever the result was today we needed to win the next three games.

"But I believe in this squad to bounce back and be much better against Samoa in eight days' time."

Townsend also revealed that Hamish Watson's involvement in the remaining games is in doubt after he suffered what looks to be a serious knee injury. The flanker was in clear pain after his knee buckled when he was caught between Irish props Cian Healy and Tadhg Furlong.

"Hamish is our only injury concern," Townsend said. "He had a knee injury that we will be hopefully getting more information on tonight with a scan.

"It doesn't look good when a player is stretchered off the field, so hopefully we'll know more later tonight.

"It would be bad luck for any player if he misses the World Cup. We had Sam Skinner miss out on selection ahead of the World Cup.

"But we have always presumed that there will be people who will miss the World Cup after each game that we play. Let's hope that's not the case with Hamish.

"The good news is that Jamie Ritchie will be available for our next game after returning to full training.

"Magnus [Bradbury] is obviously still here in Japan too. We held onto him just in case we didn't have any luck with injuries this weekend. So if Hamish was to miss out then Magnus would be the obvious choice to replace him."

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