Second Serve: Your new weekly tennis briefing

In the latest edition of Second Serve, our new weekly snapshot of the tours, BBC tennis reporter Jonathan Jurejko looks at the key talking points following the Miami Open.

Jannik Sinner isn't even allowed to play competitive tennis, yet he's still strengthened his grip as the world's leading men's player.

Sinner, of course, is almost halfway through a three-month ban for a doping offence, which ruled him out of the 'Sunshine Double' in Indian Wells and Miami.

But he watched on as his nearest rivals - Alexander Zverev and Carlos Alcaraz - both fumbled the chance to significantly narrow the gap at the top of the ATP rankings.

It looks increasingly likely Sinner will lead the way when he returns in Rome at the start of May.

Sinner still holds a lead of 2,685 ranking points over Zverev, while Alcaraz is 3,610 adrift.

With 1,000 points available to the Monte Carlo and Madrid champions, plus 500 for winning Barcelona or Munich, a slim opportunity for Zverev remains.

Seizing the chance to overtake Sinner had been on Zverev's mind. Then he started, by his own admission, "playing terrible".

Since losing in the Australian Open final, Zverev has won only six of 11 matches across the five tournaments he has played

The world number two was beaten by American qualifier Learner Tien in the Acapulco second round, 43rd-ranked Tallon Griekspoor in the Indian Wells second round, and France's Arthur Fils in the Miami Open fourth round.

"I have been losing a lot of matches that I feel like I couldn't control lately," Zverev said after his Miami exit.

"I have to look at myself more than anything else."

And what about Alcaraz? As we discussed in last week's Second Serve, he also has some soul-searching to do.

Sinner is not the only one to have cemented his spot as the world's leading player this month - although Aryna Sabalenka has actually done it herself on the court.

After winning Miami and finishing runner-up at Indian Wells, she has moved more than 3,000 points clear of second-placed Iga Swiatek in the WTA rankings.

Sabalenka's dominance - having won the most matches this year (23) and reached the most finals (four) - will be secure until the French Open at the very least.

What else happened in Miami?

• Novak Djokovic was denied his 100th ATP title as Czech teenager Jakub Mensik won a first - having almost pulled out of his opening match.

• Emma Raducanu played her best tennis since winning the 2021 US Open. Now she needs to build on her encouraging displays.

• Filipina teenager Alexandra Eala beat three Grand Slam champions, including second seed Swiatek, in a dream run to the semi-finals.

• That came after Swiatek was verbally abused by an "aggressive and taunting" fan during practice.

Mensik's stock - and his ranking - has shot up after his exploits in Miami.

Moving into the world's top 25 after his breakout run, the 19-year-old Czech is comfortably the biggest climber in the top 100.

Jacob Fearnley is the new British number two after reaching the Miami second round, while Croatian former top-20 player Borna Coric made a notable jump after winning a Challenger title on home soil.

Eala is the biggest climber in the WTA top 100, with Raducanu and Romania's Anca Todoni - a 20-year-old who won a WTA 125 title in Turkey - also enjoying significant rises.

Many of the world's best are taking a week off as they change continents and surfaces before the European clay-court swing.

But top American stars Jessica Pegula and Madison Keys will head a strong WTA field at the Charleston Open.

Three ATP events take place in Houston, Marrakech and Bucharest, although only two of the world's top 20 - Tommy Paul and Frances Tiafoe - are in action.

Women's singles

Raducanu's run to a first WTA 1,000 quarter-final was the biggest British story last week, while Sonay Kartal's recent rise continued as she secured another career high ranking of 61st.

On the second-tier WTA 125 Tour, former British number one Heather Watson reached the semi-finals of the Puerta Vallarta Open in Mexico.

In Vacaria, Brazil, 24-year-old Briton Fran Jones beat France's Leolia JeanJean 1-6 6-4 6-1 to win the W75 event - an ITF Women's World Tennis Tour event in the tier below the WTA Tour.

Men's singles

With Jack Draper, Jacob Fearnley and Cameron Norrie all out of Miami, attention turned to below the main tour.

Former British number one Dan Evans lost in the first round of a Challenger in Naples, dropping out of the world's top 200 as a result.

Julian Cash and Lloyd Glasspool have won two titles in their first full season together

Men's doubles

Julian Cash and Lloyd Glasspool demonstrated Britain's strength in depth by reaching their biggest final together.

The sixth seeds had to settle for the Miami runners-up prize, however, after losing 7-6 (7-3) 6-3 to top seeds Marcelo Arevalo and Mate Pavic.

Women's doubles

Olivia Nicholls and her Slovakian partner Tereza Mihalikova were unable to replicate their run to the Indian Wells final, going out in the second round in Miami.

What is Second Serve?

With so many professional tennis tournaments taking place across the world, and across so many levels, it can be hard to keep up with everything from one week to the next.

As part of BBC Sport's commitment to offer more for tennis fans, Second Serve will be your weekly round-up of the biggest stories in the sport.

As well as the main talking point, you can see which ATP and WTA players are making significant progress - or struggling for form, how the British contingent are doing and what the next stops on the calendars are.

You can also sign up to get the latest tennis news from BBC Sport delivered straight to your mobile phone.