The Seahawks led 3-0 after the first quarter, but the Texans scored 20 unanswered points in the second quarter, building a 20-3 halftime lead. However, the Seahawks outscored the Texans 17-0 in the third and fourth quarters. With less than three minutes to go, and the Texans leading 20-13, Matt Schaub's pass on 3rd down was picked off by Richard Sherman and returned 58 yards for a pick six, allowing the Seahawks to tie the game and force overtime. The Seahawks would go on to win the game in overtime by a final score of 23-20. With the win, the Seahawks would open the season with a 4-0 record for the first time in franchise history.. How many points were the Texans leading by at the end of the first half?