Root goes into the fourth day of the second Test unbeaten on 178 with England leading by a massive 566 after ending the third day on 333 for five.
But the Yorkshireman is not thinking about his first double hundred for England, who will be looking to take a 2-0 lead in the five-match series against Australia by taking victory at Lord's.
Root told Sky Sports: "I'm not thinking too far ahead. I'm just thinking of small targets like I've done all game."
After England had lost three quick wickets last night the pressure was on, but Root responded to the challenge, batting watchfully and later kicking on after passing a century for the first time at Lord's as an England player.
He said: "We knew going into today that we were going to have to play some really good cricket. We had to scrap for a bit and earn the right to score runs later in the day."
Of his century, Root added: "It was pretty special. As a kid growing up, playing in the Ashes is the pinnacle and to get a hundred, at Lord's as well, is a nice feeling.
"It was tough. They bowled really well all morning."
Root, who was picked as opener at the expense of Nick Compton, said he was not concerned at which place in the order he was asked to play.
"You just want to score runs. It doesn't really matter where you play. For me I just want to keep contributing to the side. Whether it's up top or in the middle.
"I just want to keep scoring as many runs as I can for England."