Boro were outside the bottom three on goal difference alone when Warnock replaced Jonathan Woodgate last month, but three wins from six since then has lifted them up to 18th.
The Smoggies showed true fighting spirit to battle back from a goal down against Reading on Tuesday, with Patrick Roberts playing a part in both goals as Boro claimed a 2-1 win.
That victory - a fourth away from home in five matches - leaves Warnock's men five points above the relegation zone with two games to go.
Survival is not quite assured just yet, then, but one more point from those games against Cardiff and Sheffield Wednesday will surely be enough.
It will mark yet another impressive achievement for Warnock in a career that has seen him earn a record eight promotions, the latest with Cardiff a couple of years ago.
Warnock is still loved in South Wales, but all that will go out of the window on Saturday as the veteran manager aims to derail his old club's promotion push.
City beat Derby County 2-1 on Tuesday to open up a two-point gap on the chasing pack in the final promotion spot, despite losing back-to-back matches last week.
Given the tight nature of the playoff battle, with three points separating Cardiff, Millwall and Swansea City, the Bluebirds may yet need to win both of their remaining games.
Cardiff had won three away games in a row before going down 2-0 to Fulham last week and have taken more points on their travels (28) than Boro have managed at home (26) this term.
City have a good record against Middlesbrough, too, winning the last three meetings by the same 1-0 scoreline, including their most recent trip to the Riverside in October 2017.
Middlesbrough's Championship form: WLLWLW
Cardiff City's Championship form: WDWLLW
After naming an unchanged side for a couple of matches, Warnock made four alterations to his starting lineup for the trip to Reading.
Roberts in particular impressed against Reading and Warnock may well opt to field the same XI on Saturday, barring any injury issues in the four days between the matches.
Tomlin's fitness remains a concern, though, and Harris may well opt to use him as an impact sub in the North-East this weekend.
Middlesbrough possible starting lineup:
Pears; Dijksteel, Fry, Friend, Johnson; Howson, Saville; Spence, Roberts, Tavernier; Fletcher
Cardiff City possible starting lineup:
Smithies; Bacuna, Morrison, Nelson, Bennett; Ralls, Vaulks, Pack; Mendez-Laing, Glatzel, Hoilett
We say: Middlesbrough 0-1 Cardiff City
Middlesbrough are without a home win since Boxing Day, losing half of their 10 matches at the Riverside Stadium since then. A defeat to Fulham last week aside, Cardiff have been in great form on their travels and we expect them to make it four wins in a row against Boro - all the by the same scoreline - in this weekend's clash.