It was late delight for the Chairboys as they came from behind to defeat Crewe Alexandra 3-2 at Adams Park.
Gareth Ainsworth made two changes to the side that beat Colchester United last time out - with Adam El-Abd and Sam Saunders coming in for Anthony Stewart and Luke O'Nien, who sat out after picking up a knock at the weekend.
Wanderers fashioned the game's first chance when Marcus Bean threaded it through to Ebere Eze in the box. The midfielder took a touch and fired his shot wide of the near post after 3 minutes.
Joe Jacobson tried his luck from 25-yards in the 13th minute after the ball was half cleared. The full-back's drive forced keeper Ben Garratt into a save low to his right.
Eze was looking lively in the first period, linking up with Adebayo Akinfenwa in the box before seeing his shot blocked behind for a corner just past the quarter-hour mark.
A long ball over the top from Scott Brown had Bayo's name written all over it on 23 minutes, with the striker connecting with a header though Garratt was equal to it on this occassion.
A beautiful cross-field ball from El-Abd picked out Tyson on 25 minutes. The forward crossed to bayo, who teed up Marcus Bean who saw his first-time shot blocked.
The Chairboys' dominance was rewarded on 29 minutes as Mackail-Smith made it two in two games. The striker latched onto Akinfenwa's flick-on, rounded the keeper, and eventually converted to give the home side a deserved lead.
After a comfortable spell for Wanderers, Crewe's first sniff of goal handed them the equaliser shortly before half-time. Chris Porter rose highest to nod down Perry Ng's deep cross and Chris Dagnall was there to prod home.
Zoumana Bakayogo was booked for a late challenge on Dan Scarr in first half injury time with the whistle coming soon after the defender was treated.
Half-time: Wycombe 1-1 Crewe
The first chance of the second half went the way of the hosts. Jacobson aimed a corner to the back post which was headed back across goal by Scarr, which in turn found the head of defensive partner El-Abd who hit over on to the roof of the net.
Then Crewe threatened from a corner on 50 minutes, but a powerful low drive couldn't beat Brown despite a deflection from Dagnall.
Up the other end Eze smacked the bar a minute later after hitting a sumptuous curling effort from Tyson's lay-off.
The ever-present QPR loanee did well to find space for himself on 55 minutes, before forcing Garatt into a save down to his left as Wanderers pressed for the lead.
Scarr saw the ball drop to him from a deep-cross out from the left, though he could only hit into the terrace on 57' and Akinfenwa would then see his shot go over the top after chesting the ball down on the edge.
The Chairboys kept coming - A long clearance from Brown was nodded into the path of Bayo by CMS, but his first touch let him down and the ball got away shortly before the hour-mark.
A minute later Akinfenwa beat the keeper, but not the defender as Eddie Nolan hooked his back-post header off the line after Jacobson' inviting cross.
Mackail-Smith appeared to be hauled down in the box on 64 minutes, but referee Andy Haines thought not and booked him for simulation.
Despite Wycombe's pressure, it would be Crewe who would take the lead on the break on 67 minutes. Dagnall bagged a brace as he slotted past Brown following a flick-on from a route one ball. Two chances, two goals for the Alex.
Another blow for Wycombe came in the 70th minute as Dan Scarr went off after his first half knock appeared to have taken its toll. Anthony Stewart came on to replace him.
Mackail-Smith made way for Josh Umerah on 73 minutes as Gareth Ainsworth looked to salvage the game with just over 15 remaining.
The Chairboys continued their assault on the Crewe goal. Harriman's cross was volleyed goalwards by Tyson on the stretch at the back-post but it was stopped superbly by Garratt on 77'.
The last roll of the dice from the sidelines was made as Nick Freeman came in place of Saunders with 10 minutes remaining.
Harriman picked out Akinfenwa again on 86, but the big man could only get underneath it and headed over with time running out.
No more crosses, the right back took it upon himself to draw the game level with less than three minutes of normal time remaining. A long punt from Brown was touched back by Akinfenwa to Eze who then set Tyson off down the wing. The forward found Harriman who smashed it into the far corner first time.
What was good, got a whole lot better on the 90 minute mark. Eze picked out Tyson on the left and off he went. He powered his way to the box and sent a thunderous strike past Garratt sending the home fans wild.
3-2 is how it finished in a pulsating fixture at Adams Park.
£1 Draw (£393) - 15053
£2 Draw (£87) - 29309
Attendance: 3,295 (112 Away)
Man of the Match: Ebere Eze