The Mercedes driver's fastest lap of 1 minute, 23.599 seconds was 0.038 faster than Sebastian Vettel, who is aiming for a third consecutive victory at the Australian GP.
Vettel was not far off the pace of the Red Bulls in the second session but he slid through the grass and complained of handling problems on the team radio.
After winter testing, Hamilton said he thought Ferrari were a half-second quicker than Mercedes.
Sebastian Vettel, who has won in Melbourne for the past two years, could only manage fifth, almost a second adrift of arch-rival Hamilton, while Ferrari partner Charles Leclerc struggled to ninth, straddling the kerb and spinning as he pushed hard late in the day.
Alfa Romeo's Kimi Raikkonen was fifth quickest - just 0.099secs behind his former Ferrari team-mate Vettel.
Ahead of the Australian Grand Prix, Hamilton said it was "not hard to read" Mercedes' testing form, and insisted the team wasn't playing mind games with its pre-season estimations.
The Renaults of Nico Hulkenberg and Daniel Ricciardo were sixth and seventh respectively.
Vettel later bolted on softs and put in a lap of 1m23.473s to go fifth fastest, subsequently describing the vehicle as "still a bit wobbly" over the radio.
"When we get to Q2 and they start to crank the engines up, that's when the story will start to unfold of where are Honda".
Ahead of qualifying this afternoon Wide World of Sports looks at the big issues raised by the first two practice sessions.
"It was a tricky day for us - it was probably a tricky day for everyone".
"We don't actively encourage our drivers to go and take a lot of risk, but they've got to live their lives and have some fun along the way".
Thai driver Alex Albon had a debut to forget with Toro Rosso, leading that group of four outlying drivers at the back of the field after a scrappy two sessions, including a crash early in the day.
"I think it's really about finishing races and analysing and making sure you are getting as many points as you can, of course, but I'm not really one for needing to stamp authority".
In between, FIA President Jean Todt and Formula 1 chairman Chase Carey attended a news conference with started with a minute of silence in memory of race director Charlie Whiting, who died in Melbourne on Thursday from a pulmonary embolism.
In its invitation, Apple did not specify the focus of the event and gave a single-line description: "It's show time". If anything, we may only see shows that Apple is already producing, like Carpool Karaoke , included at launch.
She has lately become the queen of the Hallmark Channel with her holiday movies and the series "When Calls the Heart". Indeed, actress Felicity Huffman , known for her role in Desperate Housewives , was arrested Tuesday for mail fraud.
Thomas says this bribery scheme underlines how important people think it is to go to a college with name brand recognition. The accusations say some of the efforts attempted to get athletic scholarships and others paid for high test scores.
John Vandemoor, a former Stanford University sailing coach, is also scheduled to plead guilty to racketeering conspiracy charges. Macy has not been charged nor have the colleges, which all released statements saying they knew nothing about the scheme.
Ronaldo had experienced a quiet Champions League campaign before Tuesday night, having scored just once in six total appearances. Juventus boss Massimiliano Allegri was anxious his side could lose their cool from the first leg but his fears were unfounded.
The move would shake up Germany's security sector, which relies on intelligence from the NSA, CIA, and other American agencies. And other countries have issued security warnings about Huawei and China, including the Czech Republic and Lithuania .
The couple will reportedly take their vows over a three-day celebration at the Jio World Centre in Mumbai's Bandra Kurla Complex. The 55-year-old, dressed in a pink saree coupled with diamond jewellery, presented a classical performance.
Kate, on the other hand, opted for a bold look with a red coat dress by Catherine Walker paired with a matching red fascinator. Canada is a special place for Meghan, who was living in Toronto to film Suits before moving to England to be with Harry.
Some of Jade's online videos and photos were paid partnerships with Amazon .com Inc and Hewlett-Packard Enterprise Co. Despite making the choice to attend post-secondary, Olivia has admitted that school isn't really her thing.
Civil War, Johnson was impeached in 1868 after firing his secretary of war, only to be acquitted by the Senate. Chabot offered some advice to his fellow Judiciary Committee members: "Move forward with great caution".
Jordan Travis transferred in from Louisville but is awaiting to hear whether he will get a waiver for immediate eligibility. Since the tumultuous departure of Deondre Francois , FSU has been desperately pursuing help at the quarterback position.
Tiger Woods 'feeling good' at Sawgrass
It all starts to unfold today, with only 23 players having experienced the March conditions before the move to May in 2007. Tiger Woods has admitted the neck strain that forced him to pull out last week was caused by his four back surgeries.
Android Q beta launches today, available to all Pixel phones
Android Q also introduces Settings Panels, a new API that allows apps to show system settings to users inside of an application. Once you're enrolled, you'll continue to be updated to every new version of the Android Q beta automatically, over-the-air.
Facebook says outage is 'not related to a DDoS attack'
The world has been freaking out today after not one , but two of the biggest social media platforms have been down for some users. Due to the outage advertisers are losing money and it seems that the company is planning to issue refunds to the advertisers.
Odell Beckham Jr. Traded To Cleveland Browns
The Giants trading Beckham would likely take a pretty strong haul, but the Browns aren't shying away from making big moves. They'll have to eat $ 16 million in dead money against the salary cap this season, but will gain $5 million in cap room.