The 40-yard dash remains a magic number for scouting football players. And though it should be one of Darius Fleming’s strengths, whether he runs a 4.65 or a 4.72 at the NFL Scouting Combine on Monday, the former St.  Rita and Notre Dame standout doesn’t think it makes a difference in how successful he’ll be in the NFL.

‘‘I really don’t. And I think the teams know it as well,’’ Fleming said. ‘‘It’s something they have to do. It tells you a little bit about how fast a person is. But when it comes down to it, if you know how to play football, you know how to play football.’’

An outside linebacker, Fleming rarely runs 40 yards on a football field. On a rare opportunity, after an interception against Stanford last season, he went 34 yards before being tackled by Coby Fleener. So while he was caught from behind — by a tight end with wide receiver speed who could be a first-round draft pick — he also intercepted a quarterback, Andrew Luck, who is likely to be the No. 1 pick in the draft.

Ultimately, it still comes down to whether you can play football. Or should.

‘‘That’s why my drill work is so important,’’ Fleming said. ‘‘I’m not running a 4.6 in drill work. I’m running at game speed. I think that’s going to play a huge part in how they evaluate me.’’

Fleming has been working six days a week for the last seven weeks to get himself in the best shape of his life in preparation for the combine this weekend. It’s not make-or-break. But for a player projected to be a mid-to-late-round pick such as Fleming, it’s more than perfunctory.

‘‘This is where everybody says you can make your money,’’ said Dave Lee, Fleming’s agent. ‘‘If he does well, he can get drafted higher.’’

That’s why Lee’s agency has invested more than $10,000 in the process. Fleming has been working out in a combine-specific training program at EFT Sports Performance in Highland Park under the tutelage of noted fitness trainer Elias Karras.

It’s up to Karras to get Fleming healthy, get his weight and body fat right and prepare him for not only the 40 but drills and workouts specific to the combine — the short shuttle, the three-cone drill, the long shuttle, the 60-yard shuttle and the vertical and broad jumps, plus positional work.

‘‘I didn’t know what to expect going into it,’’ Fleming said. ‘‘But I don’t worry about it because I have an awesome trainer and I trust everything he does.’’

Karras has been training pro athletes for 10 years. EFT trains more than 30 NFL players, including Devin Hester, Johnny Knox, Tommie Harris, Mark Anderson and Kelvin Hayden.

But it’s his success with draft prospects that has increased business in recent years, including Northern Illinois’ Larry English, Rutgers’ Jason McCourty, South Florida’s Jacquian Williams and Oregon’s Jairus Byrd. McCourty, a cornerback, had a free-agent grade in 2009 but ran a 4.3 in the 40 on his Pro Day and was drafted in the sixth round by the Tennessee Titans. After Byrd ran 4.68 at his Pro Day in 2009, he spent a week with Karras at EFT and ran 4.60 in a private workout. He was drafted in the second round by the Bills.

Karras does his homework, too. He compiles a list of the top five and top 10 marks in position drills from the previous year’s combine and aims to have each athlete hit those marks.

‘‘It’s the numbers and the film,’’ Karras said. ‘‘You want the numbers that pop out so that [the NFL evaluators] can go back to the film. ‘Let me take a look at this kid again. Maybe he’s better than we thought.’ Sometimes a kid doesn’t look fast on film.

‘‘It’s up to Darius to wow ’em in the interview, wow ’em in the film work and chalkboard, shoot for top 10s in all the categories for the combine, and then at the Pro Day kill his skill work. That’s where we really see movement, the skill work.’’

Fleming said he was nervous about the combine at first but is confident after working with Karras that he’s in shape to do well.

‘‘That’s why it’s so exciting,’’ he said. ‘‘As they continue to coach you, you actually see improvement. It makes you want to keep working that much harder.’’