Pair of guards look good early on Day 4

Note: All combine times are unofficial until the NFL releases results following the final workouts of the week.

Here's a look at some offensive linemen who have stood out early during Saturday morning workouts:

• Two linemen posted impressive 10-yard splits in the 40-yard dash. The first is California (Pa.) G Rishaw Johnson, whose 1.77-second split confirms the initial explosiveness you see on film, and is below the four-year combine average (1.88) for guards. Johnson (6-foot-3, 313 pounds) is as explosive as they come along the interior and gets to the second level quickly. He is solidly in the middle rounds at this point.

The second is 345-pound Georgia G Cordy Glenn, whose split of 1.76 shows impressive burst for a player with his massive frame. Glenn didn't show great lateral quickness or mobility when asked to change directions in space, but he did a nice job of beating the defender to the corner during a drill designed to simulate a rusher coming off the edge. Glenn has risen quickly after a strong week at the Senior Bowl and is a first-round possibility.

• Stanford G David DeCastro and Baylor C Phillip Blake didn't shine in the edge-rush drill, but that's somewhat expected from players who line up on the interior. However, Utah OTs Tony Bergstrom and John Cullen both need to show a quicker kick step and slide more fluidly if they hope to make their living on the edge.

• There is plenty of speculation about the durability of Florida State OT Andrew Datko, who has had two shoulder surgeries in the last year, but his footwork was impressive in protection drills. Datko needs to sink his hips more, but he looked fluid getting to the edge and when mirroring pass rushers. He is fighting to stay in the middle rounds because of those medical questions.

• Iowa G Adam Gettis did a great job of bending his knees, playing upright and staying balance when asked to mirror. South Dakota OT Tom Compton showed just average foot speed, but he also shuffles well and stays balanced