The 6-2, 306 defensive tackle was the 62nd player chosen in the draft. He was at his home in Mobile when he heard his name called.
Marks is the first Auburn player drafted by the Titans since they picked defensive tackle Gary Walker in 1995 when the team was in Houston.
Marks said he wasn't sure who would draft him. "I had no idea who would pick me and when I'd be picked. I just sat around waiting and it just happened."
The lineman did know the Titans were interested because he visited Tennessee earlier this month.
"The Titans complex was the only facility that I went to visit and I really enjoyed it," Marks said. "It was a lot like Auburn's so I felt very familiar with it. I really liked the D-line coaches and the way that they coach. I really liked my visit and enjoyed it."
Asked if he was surprised by where he was selected, Marks said, "A lot of people had me in the second or third round, but I saw a lot of guys go ahead of me that I didn't expect. But it really didn't matter to me. It just feels great."
Commenting on how he felt when he got the news from Tennessee head coach Jeff Fisher, Marks said, "Oh man, I just went crazy. I went crazy. When I went to visit the Titans, I asked Coach Fisher how it all works on draft day and he asked if I really wanted to know and he told me. When he just called me, he said, 'Didn't I tell you that it was going to be a great feeling?'"
Sen'Derrick Marks is shown as a redshirt junior for the Tigers.
The first two rounds of the draft were held on Saturday at Radio City Music Hall in New York. Rounds three through seven will begin at 9 a.m. CDT on Sunday and several more Auburn players could be drafted such as offensive guard Tyronne Green and cornerback Jerraud Powers.
Powers, like Marks, was a redshirt junior who decided not to return to college in 2009 for his fifth year of eligibility.
Marks was in on 32 tackles last season as he battled through injuries. He played in 11 of Auburn's 12 games. He had two sacks and 10 total tackles for lost yardage. He had a pair of sacks, two quarterback pressures, deflected two passes and blocked a kick.
He had 38 total tackles with 3 1/2 sacks and 11 tackles for lost yardage as a full-time starter in 2006 as a redshirt freshman.
In 2007 Marks again started every game and was in on 43 tackles with two sacks and nine tackles for losses.
In the five previous seasons, the Tigers have had 23 players drafted by NFL teams.