If a middle order batsman gets injured then they can just plant Compton at 4 or 5 (he was a makeshift opener for England anyway) or stick Root back into the middle order and have Compton and Cook open.
From what Flower has said its opener or nothing so definately your second option.
BBC Sport - Ashes 2013: 'Hardened' England ready for Australia
Team director Andy Flower says England are "match-hardened" for the Ashes after Graeme Swann took five wickets in a win over Essex.
England completed a 228-run win over Essex on Wednesday in their final match before the first Test against Australia begins on 10 July.
"This bunch of cricketers have fought a lot of campaigns and won a lot together," said Flower.
"They are match-hardened - that should give them a lot of confidence."
England bowled the county side out for 186 on the final afternoon at Chelmsford, with Swann taking 5-58.
Earlier in the four-day match, the spinner had been struck on the arm while batting by Essex paceman Tymal Mills.
X-rays revealed he had suffered only bruising, and the Nottinghamshire man was able to bowl 20.3 overs on the final day.
"There were great concerns about Swann, we thought he might have cracked his ulna [elbow bone]," said Zimbabwean Flower. "It would have been a serious blow.
"It was important for him to get those overs done and to show that sort of quality."
Durham pace bowler Graham Onions also weighed in with four wickets, but would have to get past Steven Finn and Tim Bresnan in order to earn a place in the England side for the Trent Bridge Test.
Flower said he was already clear which players would make up both the squad and the final team for the first Ashes encounter.
"We were pretty clear before this game about what our squad would be and what our XI will be," he said.
However, England do have fitness concerns over Stuart Broad, who missed the game against Essex with a right shoulder injury which has been treated with a cortisone injection.
The Nottinghamshire all-rounder bowled on the outfield during lunch on the final day at Chelmsford.
"Broad should be OK," said Flower, who took charge of the England team in 2009. "That was his first effort at bowling and I was pretty surprised.
"I anticipate him being fit for the first Test, but he could not have played in this game."
England began the day on 217-3 in their second innings and batted on for an hour of the morning session before declaring on 279-4, setting Essex a notional 415 to win.
Ashes itinerary
In that time, Jonny Bairstow, likely to bat at number six in the first Test after Joe Root's elevation up the order at the expense of Nick Compton, made 28 before being bowled playing across the line at Boyd Rankin.
Bairstow was part of the England squad for the Champions Trophy but has played only one domestic Twenty20 game since the Test series against New Zealand finished in May, so was promoted up the order to spend more time in the middle.
"We felt that he needed more time in the middle because he had those three or four weeks without cricket while he was with the Champions Trophy squad," added Flower.
"He's had what he's had, there's nothing more we can do about it."
Since being left out of the England squad for the Essex game, Compton has made scores of 81 and 34 for Somerset against the touring Australians, then added 79 on Wednesday playing against the same opposition as a guest for Worcestershire.
Flower is pleased with Compton's performances, but said the right-hander would only come into consideration if injury or lack of form affected England's openers, rather than those in the middle order.
"It's really nice to see, it's a good reaction from him," said Flower, who led England to Ashes success in 2009 and 2010-11.
"It was nice for him to get more exposure of playing [against] an international side. It was a really good reaction from him to get runs consistently and it shows he's a good, tough fighter.
"He's obviously an opening batsman so if there was an injury to someone batting at six it doesn't mean he's the next cab off the rank."
