The Texans found themselves 28-7 behind with less than five minutes to go in the third quarter, but two touchdown passes from quarterback Matt Schaub, an interception touchdown and a last-gasp Randy Bullock field goal handed them a dramatic 31-28 win.
However, despite only clinching victory as time ran out, Johnson always believed that his side would open the season with a win.
"There was no doubt in my mind that we were going to win that game," Johnson told The AP.
"Even in the third quarter, we didn't come out playing that great, but we got it together and made it happen."
Johnson, who has been with the Texans since being selected third overall in the 2003 Draft, had 12 catches for 146 yards in the match.