Alonso's men, who have a Europa League final against Atalanta and a German Cup final versus Kaiserslautern to come this week, have not lost in any competition this season -- a run of 51 games.
Champions Bayer Leverkusen edged past Augsburg 2-1 on the last matchday on Saturday to become the first team in the history of the Bundesliga to complete a full season without a loss.
Bayer Leverkusen stretched their season-long unbeaten run to 50 games with a 5-0 win at 10-man Bochum on Sunday.
Leverkusen, the Bundesliga champions who have also reached the May 25 German Cup final, played their 49th match without defeat in all competitions, surpassing Benfica's long-standing European record set from 1963 to 1965.
Xabi Alonso's rampaging Bayer Leverkusen will have an additional incentive in Thursday's home second-leg Europa League semifinal against Roma: breaking a 59-year-old European football record.
Bundesliga champions Bayer Leverkusen extended their season-long unbeaten run to 48 games with a 5-1 win at Eintracht Frankfurt on Sunday.
Leverkusen won their first meeting with Roma in almost 20 years.
After years of heartbreak and being dubbed "Neverkusen" for their string of runners-up finishes, Bayer Leverkusen finally broke through to claim their first-ever Bundesliga title. Their 5-0 victory over Werder Bremen last week secured the trophy, marking a watershed moment in the club's 119-year history. Although they have enjoyed intermittent cup success, this league title signifies a shift in their fortunes.
"We want more. We want the (German) Cup, we want Europa League," the 42-year-old said over the stadium PA to thousands of Leverkusen fans after his side 43rd straight match without defeat.
The German equivalent of "Neverkusen" is "Vizekusen", which translates to "the champions of second place".
Leverkusen's 5-0 win over Werder Bremen at home on Sunday, including a second-half hat-trick from Florian Wirtz, sealed a first Bundesliga title in their 120-year history.
Bayer Leverkusen's record-breaking run to their first Bundesliga title was no fluke, with a 16-month plan coming to fruition.
Xabi Alonso's Bayer Leverkusen of 2023-24 stand on the cusp of greatness, with just 11 matches theoretically between them and a record undefeated season for a top-five European league team.
With 24 wins and four draws in the league this season, Leverkusen are on the cusp of going through a Bundesliga season undefeated.
Jonas Hofmann and Victor Boniface scored after coming off the bench as Bayer Leverkusen beat West Ham 2-0 at home on Thursday in their Europa League quarter-final first leg.
Leverkusen head into Thursday's home first leg against West Ham in the Europa League quarter-finals unbeaten in 41 matches this season, with 36 wins and five draws.
Bayer Leverkusen coach Xabi Alonso insisted Friday it was "still too early" to talk about the Bundesliga title despite his team being 13 points clear at the top of the table.
Bundesliga leaders Bayer Leverkusen overwhelmed second division club Fortuna Dusseldorf 4-0 on Wednesday to reach the German Cup final and stretch their unbeaten run to 40 matches across all competitions this season.
Last-gasp goals from Robert Andrich and Patrik Schick kept Bayer Leverkusen's undefeated record this season alive with a 2-1 home win over Hoffenheim on Saturday.