Wales scrum-half Mike Phillips admits he could be dropped for the second Test against South Africa on Saturday.
Scarlets number nine Gareth Davies impressed on his debut as a replacement for Phillips in Wales' 38-16 defeat against the Springboks in Durban.
Phillips says he his not taking his place "for granted".
"Everybody knows Gats [Gatland] doesn't shy away from putting relatively so-called big names on the bench," said Phillips.
"It's whoever's best for the job and as simple as that really."
Davies, 23, was the top try-scorer in the Pro12 last season.
He has been tipped to start the second Test in Nelspruit following his eye-catching cameo.
Phillips, 31, who has won 86 Wales caps, welcomes the competition for the number nine jersey.
"We've got great competition throughout the squad really and at nine especially," said Phillips.
"Gareth did really well last week when he came on so it's great for him.
"It's just great to have competition and people pushing you all the way."
Wales have never beaten the Springboks on South African soil and have struggled to beat them and the other southern hemisphere rugby superpowers Australia and New Zealand despite several close encounters.
The Springboks ran in five tries in a one-sided display in Durban.
The Racing Metro scrum-half says Wales are determined to finish the season on a high but must get off to a good start if they are to create history.
"The boys give everything every time they wear the jersey," said Phillips.
"Nobody takes it for granted and we work our socks off in training and on the park.
"Sometimes things don't go your way but we've got to learn and we've got to improve this week.
"It's the last week of the season for us. It's been a long, sort of, two seasons for us really. Last year was the Lions and things and it's all mental stuff.
"We are not going to improve as players within a week. It's all about the top two inches.
"About being there and being on song in the first 20 minutes against a quality side like South Africa, and hopefully we can push on from there."
Wales are expected to name their line-up on Thursday.