Following a disappointing draw in midweek, Milan sit sixth with five games to go, while their capital-city counterparts have soared through the pack with seven wins from their last 10 league matches.
Match preview
Though Milan are into the Champions League semi-finals and await a two-legged tussle with Inter later this month, their hopes of returning to Europe's top club competition next term have taken a hit after Wednesday's draw with Cremonese.
Indeed, it seemed that the Rossoneri were heading for defeat when they trailed their regional rivals heading into stoppage time, but Junior Messias produced a late equaliser to salvage a point which keeps them within two of fourth-placed Inter and level with Atalanta.
Amid a packed schedule, Stefano Pioli's calculated risk of fielding a weakened starting XI backfired, highlighting Milan's lack of squad depth in the process, and even throwing on Olivier Giroud, Rafael Leao and Sandro Tonali was not enough to secure just a third win in nine Serie A matches.
The outgoing Italian champions have now drawn four of their last five in the league, and they cannot continue in that vein much longer if they are to achieve the minimum objective of a top-four finish come June.
Between now and then, they face a fixture list that will pitch them against Lazio, Inter twice, and Juventus - with a potential Champions League final to follow, in the best-case scenario.
Starting that schedule against Pioli's former club on Saturday, Milan will seek revenge for a 4-0 defeat in January's reverse fixture and aim for a third straight league win over Lazio at San Siro, where they are also on an eight-game unbeaten streak in all competitions.
If Lazio caught Milan short by scoring four times from their five shots on target at Stadio Olimpico, three months later they will start as most observers' favourites against last year's Scudetto winners.
A 2-0 home victory over Sassuolo in midweek kept the Aquile above nearest challengers Juventus in the Serie A standings and very much on course for Champions League qualification.
Felipe Anderson gave Lazio the lead early on, before substitute Toma Basic sealed the deal during second-half stoppage time, helping the home side bounce back from successive defeats which had let other sides back into the hunt for second spot.
Losses against Torino and Inter had somewhat taken the shine off a superb start to spring from the capital club, but a six-point buffer to both Milan and arch-rivals Roma could be crucial in securing Maurizio Sarri's main aim.
Since the end of February, Lazio have actually taken more points than any other team throughout Serie A, but the job of confirming a top-four finish is not yet done.
Ahead of their trip north, Calcio's clean-sheet supremos have also conceded just three goals in their last six league games on the road, so they may be confident of shutting out Milan and then concluding their campaign against four more modest opponents.
AC Milan Serie A form:
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D
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D
AC Milan form (all competitions):
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D
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W
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D
Lazio Serie A form:
W
W
W
L
L
W
Team News
With Fikayo Tomori returning from suspension and several other established stars back in the Milan lineup, Stefano Pioli's starting XI should look quite different to that which toiled so badly on Wednesday.
Only Tommaso Pobega and Zlatan Ibrahimovic are set to miss out due to injury, so the hosts have an almost full squad from which to choose.
Therefore, Sandro Tonali, Theo Hernandez and Rafael Leao will be back in action from the first whistle, with Olivier Giroud replacing Divock Origi up front.
Danilo Cataldi remains Lazio's main injury concern, as he battles to recover from a calf problem, and it could be a settled side which takes to the field this weekend.
Maurizio Sarri's most likely change would be bringing in ex-Milan defender Alessio Romagnoli - who is back from a ban - for Patric, while Elseid Hysaj is a strong contender for promotion from the bench.
The Biancocelesti's front three is set to remain unchanged, with Felipe Anderson and Mattia Zaccagni - who both scored in January's reverse fixture - operating either side of captain Ciro Immobile.
AC Milan possible starting lineup:
Maignan; Calabria, Tomori, Kalulu, Hernandez; Bennacer, Tonali; Saelemaekers, Diaz, Leao; Giroud
Lazio possible starting lineup:
Provedel; Marusic, Romagnoli, Casale, Hysaj; Milinkovic-Savic, Antonio, Alberto; Anderson, Immobile, Zaccagni
We say: AC Milan 1-1 Lazio
Lazio have won nine of their 16 away games in Serie A this season, but a trip to San Siro presents its own unique challenge, and they may have to settle for a draw on this occasion.