United States midfielder Kellyn Acosta says the Americans will target Wales captain Gareth Bale in their World Cup Group B clash on Monday.

Acosta is only too aware of the threat posed by the former Real Madrid star after spending the past four months as a team-mate of the Welsh skipper at Los Angeles FC.

Two weeks ago, Bale was the hero of LAFC's MLS Cup victory, demonstrating his knack of rising to the big occasion with a 128th-minute equaliser to force a penalty shoot-out against the Philadelphia Union.

Acosta says Bale's headed goal -- when he outjumped giant Philadelphia defender Jack Elliott -- underscored the need to keep a close eye on the Wales talisman.

"If you give a player like Gareth time and space he will exploit you, as you saw in the MLS Cup final," Acosta said.

"Everyone knows who he is. He's a guy that's super-decorated, he's a guy who's won everything. I've had the opportunity to share the field with him and know his tendencies day in day out.

"For us we know we have to limit his time and space. He's a very dangerous player and he's going to be a catalyst for them. We've got to literally start kicking him around the field a little bit. Make him feel us. 

"Let him be comfortable and he will hurt you."

At 33, hobbled by recent injuries and well short of full match sharpness, Bale is a long way from the rampaging force of nature that persuaded Real Madrid to pay £85 million ($101 million) for his services -- then a world record -- in 2013.

However, the five-time Champions League winner was the driving force of a successful qualification campaign that ended up with a return to the World Cup for the first time since 1958.

US captain Christian Pulisic said that despite Bale's limited playing time -- his 23-minute cameo in the MLS Cup final on November 6 was his first appearance since October 2 -- the Welsh captain will be ready. 

"He's a top player, there's no doubt about it, what he’s accomplished in his career," Pulisic said this week. 

"He's played at the highest level. He knows what it takes. I'm sure he'll be ready. Whether he is at the absolute top of his game, it doesn't matter."

Bale, for his part, says he is fully fit heading into Monday's opener at the 40,000-capacity Ahmad Bin Ali Stadium on the western outskirts of Doha, in a game that will kick off at 10:00 pm local time (1900 GMT).

"I'm fully fit and ready to go. If I need to play three 90s, I'll play three 90s," Bale said shortly before departing for Qatar.

"It's been difficult, mentally more than anything. I guess for everybody, the last three or four weeks, it's been difficult, even hearing stories of players going down and knowing they're going to miss the World Cup."