Lancaster hails two-try hero Brown
The hosts launched the World Cup with a 35-11 win over Fiji on Friday.
The four-try success at Twickenham also gave England a bonus point, with fullback Brown's scores in each half helping subdue a Fiji side who were in touch for much of the match.
"Brownie was excellent. His ability to beat the first defender is a great trait and he inspires the team, he plays, with such courage, pace and power," said Lancaster.
"He lifted the team in the second half by the scruff of the neck."
The bonus point was achieved with the last play of the game when the television match official awarded a try to replacement forward Billy Vunipola. But the final scoreline disguised how Fiji had frustrated England for long periods.
"They certainly made us work hard for it," said Lancaster.
"It was a tough first game for us," added Lancaster, whose side are in the so-called 'pool of death' with Australia and Wales.
"Fiji will cause every team problems.. but we scored four tries and got a bonus point.
"There are areas we need to work on. We need to have a look at a couple of scrum penalties and we need to be more direct — I thought we did that in the last 20 minutes," explained the coach, who saw England up their tempo after he brought on a welter of replacements
For Fiji coach John McKee, whose side have never beaten England, it was a case of what might have been.
"There's disappointment in the dressing room, we felt we had them under pressure at times but critical turnovers stopped us from building momentum," said McKee.
"If we could have picked up three or six points when the score was 18-11 (to England), the final 20 minutes could have been different.
Fiji have just five days until they face Australia but a defiant McKee said: "This pool is not decided tonight that's for sure."
Agence France-Presse