England's Jason Roy must keep a clear mind to end poor run, says Kumar Sangakkara

Opener Jason Roy needs to keep a clear mind and re-focus on batting basics to rediscover his form for England, says Kumar Sangakkara.

Roy's wretched run extended to 64 runs in eight ODI innings when he was bowled leg-stump by New Zealand's Adam Milne for 13 in the ICC Champions Trophy clash in Cardiff.

England skipper Eoin Morgan backed Roy ahead of the tournament, saying the Surrey batsman will open the batting throughout, and Sangakkara welcomed that vote of confidence.

"I feel a bit sorry for Jason," said the Sri Lankan legend on Sky Sports 2. "I've played with him at Surrey for three seasons and he's a fantastic player and a very important player for the England cause.

"Sometimes it's not just about being mentally strong and imposing and walking with a swagger, it's also about being mentally skilled and being very smart - reading situations and pitch conditions, and the state of your game when you are in.

"I think Jason has just been slightly confused at times - sometimes taking the wrong options and trying to do a bit too much, probably thinking about how he's batted before and trying to rediscover that form.

"It's important for Jason to keep a clear mind; he's got a thundering vote of confidence from his skipper and the coaching staff back him because they see the importance of the role that Jason plays in the side.

"He just needs to keep things simple and moving along by rotating strike and maybe allowing Alex Hales to take the lead and scoring runs to give the innings the impetus and momentum that it needs. He can maybe take a backseat and allow himself to get into rhythm and get into form.

"Form is also a lot to do with mind-set and timing. Sometimes when you say a batsman is out of form you see him struggling for timing; but in my view timing is not just about a guy walking in and pushing gently at the ball and you see it flying to the boundary, every day you feel different.

"You wake up, your body might be stiffer, your body might be different, the bowling might change.

"So when you do walk into bat and you use the term give yourself some time and play yourself in, it actually means in my mind allowing yourself the time to fall into rhythm, into sync with how you feel that day, with how the field is set, the pace of the wicket and the pace of the bowling.

"Some days it falls into place immediately. On others you might struggle for half-an-hour or an hour then suddenly it all clicks. You just need to be smart enough to understand that and give yourself that time."

Sangakkara remains in stellar form himself and earlier this week was revealed as the Professional Cricketers' Association Player of the Month for May after scoring four centuries in all cricket, including two in the match in the drawn Specsavers County Championship match against Middlesex at Lord's.

Nevertheless, the 39-year-old is standing by his decision to retire from first-class cricket at the end of the season, bringing an end to a career spanning 134 Tests, 404 ODIs and 56 T20 Internationals.

With the benefit of that experience behind him, Sangakkara says Roy must back his own game if he is to kick on and fulfil the role asked of him by England.

"Sometimes the role that you are expected to play of being the batsman that gives England a fast start, that dominates the bowling and looks for boundaries from ball one," said Sangakkara.

"Sometimes that can actually confuse you. Sometimes you can believe in the hype and think that's exactly how you must play every day no matter what the conditions.

"Again, it is vitally important that you allow yourself some breathing time."

Live coverage of the 2017 ICC Champions Trophy continues on Sky Sports.