Izale McLeod and Richard Wood notched the two goals and although Latics tried and tried, they came away from the Checkatrade.com Stadium pointless.
It was a quiet opening to the game with both sides enjoying possession but neither having chances in front of goal.
Rhys Turner was almost presented with a chance five minutes into the game but he let the ball roll past him when maybe taking a touch was the better option.
The striker had another chance on 12 minutes but this time, Turner's touch just let him down as he raced through on goal.
Latics would rue those missed opportunities as Crawley Town took the lead on 15 minutes.
After dangerous Crawley pressure, Latics failed to deal with a cross into the box and McLeod looped his header over Joel Coleman to give the home side the lead.
Heavy Athletic pressure followed but again, the visitors were struggling to create a clear-cut opportunity.
Liam Kelly, who returned to the starting fold after injury, shot over the bar whilst Conor Wilkinson's acrobatic effort was blocked by the last defender.
Just after the half hour mark, Sadler hauled Lewis Young to the floor, earning him a yellow card, to give the home side a free kick in a dangerous position.
From that resulting free kick, the Red Devils doubled their advantage through Wood.
The defender converted Lee Fowler's ball into the box to put the home side two goals to the good.
Latics needed a response and through former Crawley Town man Mike Jones, they nearly found a way back.
Joseph Mills, who was operating in the left midfield role, was fouled 25 yards but Jones' trademark free kick was just tipped over the crossbar by the experienced Brian Jensen.
Dean Holden's men came out early for the second half and five minutes in, they almost found a way back into the game.
Kelly's through ball found the run of Carl Winchester whose low cross picked out Turner in the centre but Jensen just managed to tip the ball over the bar.
Athletic had to be careful at the other end, however, as Crawley should have really extended their lead.
McLeod, Dean Morgan and Lewis Young were causing Latics' defence a lot of trouble and and the latter headed goalwards but Kelly got back on the line to clear.
Dominic Poleon was introduced on the hour mark taking the place of Carl Winchester in a bid to get more men forward for the visitors.
That move almost paid off as two minutes later, his cross found the feet of Wilkinson but his lobbed shot went inches over the crossbar.
Latics felt they should have been awarded a penalty on 68 minutes as Kelly was bundled to the floor but the referee signalled no penalty.
The momentum was with the visitors but Jones' shot with only 20 minutes remaining from 30 yards was saved well by Jenson.
Latics were struggling to create a goalscoring opportunity and both Bove and Mellis entered the game to add attacking flair.
With ten minutes remaining, Liam Kelly flashed a 30 yard drive just wide of the post as Latics continued to press for a way back into the game.
However, they were almost caught on the counter attack two minutes later as Coleman was forced to deny Young with his feet at the back post.
Jones was presented with another chance in the final minute to score from a free kick 25 yards out but it sailed just past the post.
Crawley managed to hold on to the lead and came away with the three points.
Crawley Town: Jensen, Oyebanjo, Dickson, Wood, Bradley, Tomlin, Fowler, Elliott (Smith 80'), Young, Morgan (Edwards 74'), McLeod (Pogba 84').
Subs not used: Cofie, Youga, Bawling.
Oldham Athletic: Coleman, Brown, J.Wilson, Lockwood, Sadler, Kelly, Jones, Mills (Mellis 77'), Winchester (Poleon 61'), Turner (Bove 72'), Wilkinson.
Subs not used: Kean, Dieng, Kusunga, B.Wilson.
Goals: Crawley Town (McLeod 15', Wood, 33') 2-0 Oldham Athletic
Attendance: 2,520 (203 visiting supporters)