Serena Williams admits she feels under-cooked ahead of the start of the US Open on Monday.

Williams has only played three matches, all at the Olympics, since winning Wimbledon and the American pulled out of the tournament in Cincinnati last week with a shoulder injury.

Her preparation raises question marks about the 34-year-old’s form heading into Flushing Meadows, where she is hoping to overtake Steffi Graf’s Open era record 22 major titles.

Williams said “shoulder-wise” she is improving but admits the lack of match practice has been far from ideal.

“I have not played a lot, I haven’t practised a lot, but I’m just now starting to feel a little better,” Williams said.

“Hopefully just every day I will keep going higher. I think usually I prefer to play more coming into the final grand slam of the year, but I really don’t think there is anything we can do about it.

“You just have to make the best of every single opportunity. That’s all I can do now.”

Williams was handed a tricky first round in Friday's draw, which pitted her against two-time grand slam semi-finalist Ekaterina Makarova.

Makarova, ranked 36th in the world, lost to Williams in the last four here in 2014 but the top seed was not flustered by the awkward opening match-up.

“I think it’s okay, I’m okay with it,” Williams said.

“I think I try to look at it we all always have tough matches. I played her I think in the semis I think before. I know she’s a good player. I’ve just got to do the best I can.

“She’s a big fighter. She never really stops. I think one thing I think that’s pretty impressive is she gets a lot of balls back. You think she’s not super quick, but she is.”